BULLETIN du MUSÉUM NATIONAL d’HISTOIRE NATURELLE PUBLICATION BIMESTRIELLE zoologie 278 N* 401 SEPTEMBRE-OCTOBRE 1976 BULLETIN du MUSÉUM NATIONAL D’HISTOIRE NATURELLE 57, rue Cuvier, 75005 Paris Directeur : Pr M. Vachon. Comité directeur : Prs J. Dorst, C. Lévi et R. Laffitte. Rédacteur général : Dr M.-L. Bauchot. Secrétaire de rédaction : M me P. Dupérier. Conseiller pour l’illustration : Dr N. Halle. Le Bulletin du Muséum national d’Histoire naturelle, revue bimestrielle, paraît depuis 1895 et publie des travaux originaux relatifs aux diverses branches de la Science. Les tomes 1 à 34 (1895-1928), constituant la l re série, et les tomes 35 à 42 (1929-1970), constituant la 2 e série, étaient formés de fascicules regroupant des articles divers. 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Sciencbs phtsico-chimiqubs : France, 25 F ; Étranger, 30 F. International Standard Serial Number (ISSN) : 0027-4070. BULLETIN DU MUSÉUM NATIONAL D’HISTOIRE NATURELLE 3 e série, n° 401, septembre-octobre 1976, Zoologie 278 On four Ascidian species new in the Ionian Sea par Angelo Tursi * Résumé. — Quatre espèces peu connues d’Ascidies littorales nouvelles pour la mer Ionienne sont décrites ici. Ce sont : Pseudodistoma cyrnusense (Pérès, 1952), Aplidium hyalinum (Pérès, 1956), Phallusia ingeria Traustedt, 1883, et Molgula rheophila (Pérès, 1956). Les trois premières ont été décrites de la Méditerranée mais n’avaient pas ou peu été retrouvées, M. rheophila est ici décrite comme une espèce, Pérès la considérait comme une variété de Mol¬ gula impura Heller, 1877. Abstract. — Four interesting species of littoral Ascidians found in the Ionian Sea are descri- bed again. They are : Pseudodistoma cyrnusense (Pérès, 1952), Aplidium hyalinum (Pérès, 1956), Phallusia ingeria Traustedt, 1883, and Molgula rheophila (Pérès, 1956). While the lirst three species liad been described but rarely found in the Mediterranean Sea, probably because they were confused, as regards Molgula rheophila it is a matter of a new des¬ cription as a species since previously this species had been described as a variety of Molgula impura Heller, 1877. Riassunto. — Quattro specie interessanti di Ascidie litorali rinvenute nel Mar Ionio sono ridescritte. Esse sono : Pseudodistoma cyrnusense. (Pérès, 1952), Aplidium hyalinum (Pérès, 1956), Phallusia ingeria Traustedt, 1883, e Molgula rheophila (Pérès, 1956). Mentre le prime tre specie erano State descritte ma raramente rinvenute nel Mediterraneo, probabilmente perché confuse, per la Molgula rheophila si tratta di una nuova descrizione corne specie dato che precedentemente questa specie era stata descritta corne variété délia Molgula impura Heller, 1877. Introduction During dredgings carried out systematcally in the Ionian Sea both by the Institute of Zoology of the University of Bari, the Cerruti Marine Biology Institute of Taranto and the Laboratory of Marine Biology of Porto Cesareo (Lecce), four interesting littoral species of Ascidians were collected and they are examined here. On this subject, one must keep in mind that front the systematic point of view the fauna from the Ionian Sea and in particular that of Ascidians is largely unknown. At the moment the little information on Ascidians from the Ionian Sea has been obtained from Taranto and its two seas (« Mar Grande » and « Mar Piccolo ») based upon the research of Cerruti (1948), Parenzan (1960) and Tursi, Pastore, Panetta (1974), Tursi, Ghe- rardi, Lepore (1974), Lafargue, Tursi (1975). Recently a collection of Ascidians from Porto Cesareo (Lecce) was examined by Tursi (1971) and general study of Ascidians collected during two surveys in the Ionian Sea is in press (Tursi, 1975). * Institute of Zoology, University of Bari (Italy), 401 , 1 976 ANGELO TURSI The Ascidians discussed here are unknown on the Ionian coasts or hâve not yet been sulliciently described. The spécimens hâve been examined in the Biology Laboratory of Marine Invertebrates of the National Muséum of Natural History, in Paris, with the help of C. and F. Monniot, whose assistance is gratefully acknowledged. Materials and methods Ail the specimens corne from dredgings carried out by a triangular dredge, each side 50 cm, long dragged by a boat for about 50 m. The Ascidian specimens, preserved in 10 % neutral for- malin, were examined later following the method described by Monniot (1965). Drawings hâve been carried out by means of caméra lucida. The specimens are deposited in the Muséum national d’Histoire naturelle, Paris. Loc. : Dred. 394. Pseudodistoma cyrnusense Pérès, 1952 (Fig. 1, A-C and 2, D) The colony (fig. 2, D) is in the shape of an oval, with rounded edges, barely peduncu- lated. It is practically without incrustations except for the basal part of the peduncle where some sand may be observed. The dimensions of the colony are : 4,5 cm high ; 2,7 cm large ; 1,5 cm thick. The colour of the formolized colony is yellow-reddish. The middle part is pink and opaque owing to the presence of zooids at this level, whereas the peri- pherieal part is almost transparent and without zooids. The colony is soft on the top but it becomes harder at the peduncle level. The zooids are easily taken out from the test. The zooids, grouped in the central part, are extended lengthwise along the colony. There are no Systems and the zooids are almost parallel between them. The dimensions vary greatly from individual to individual. They are adequately developed and reach an average dimension of 11 mm on 2 mm. The examined colony shows some larvae in the oviduct, whieh increase the width of the zooids. The proportions between the thorax, the abdomen and post-abdomen are 1:1:4 (fig. 1, A) on an individual which is not very contracted and having a long post-abdomen. In an individual with a shorter post-abdomen the proportions are 1:1:2. On the aierage 5 larvae are incubated in the oviduct but I examined some zooids in which the number of larvae varied from 2 to 10. The larvae are situated immediately above the male follicles up to the basal part of the branchial sac and also in the atrial cavity. The oral, tube-shaped siphon shows 6 rounded lobes of normal dimensions. The atrial siphon, on the contrary, is more extended, tube-shaped, with 6 small lobes very flattened and often difïïcult to see owing to their contraction. The atrial siphon is often at the same level as the oral siphon and sometimes a bit higher. An interesting point to note is tliat the zooids show 3 lighter spots, one of which sur¬ rounds the top of the endostyle wliile the other two are situated on the two sides of the dorsal ganglion. These lighter spots are very visible on the formolized animal, whereas they tend to disappear in the zooids included in balsam. The musculature is not remarkable at thorax level. The number of tentacles is about 16. It is possible to count 3 rows of stigmata ; between the 3rd row and the lower part of the ASCIDIAN SPECIES NEW IN THE IONIAN SEA 977 branchial sac, remains a space nearly equal to a row of stigmata. In the branchial sac it is possible to count 15 to 20 stigmata on each side. The stomach is situated ratlier low, a bit above the intestinal loop. It is preceded by a very long oesophagus nearly equal to double the length of stomach. Tins is smooth, nearly trapezoidal. Some individuals show two thicker longitudinal lines in their stomach, simulating folds. They do not show a very clear post-stomach. The middle intestine shows a loop after which there is a stricture where the back intestine begins with two little caeca which are barely developed. The intestine goes straight up towards the branchial sac, with a weak torsion. The anus is situated al the level of the second row of stigmata. The male follicles are situated after a small ovary in the last fifth of the animal. The male follicles are scattered in the post-abdomen but they are arranged lengthwise up to heart level. The sperm duct is straight. The distance between the intestinal loop and the begin- ning of the male follicles is variable ; it may be 2/5 to 1/5 of the total length of the animal. The average number of male follicles is 30, with a minimum of 20 and maximum of 60. It must be noticed, however, that examined zooids had already passed their male period (there were very mature larvae). Two vascular processes, which are not very developed lengthwise, are also visible in the post-abdomen base. The heart is visible in the terminal part of the post-abdomen. The musculature in the post-abdomen is relatively well deve¬ loped and, in general, it is possible to count about ten muscular bundles on each side, which are collected together below the heart. The larvae (fig. 1, B-C) are very developed : I mm long by 0,5 mm large. A round ocellus is visible above a typicai otolith. Three papillae separated by four pairs of extended ampulla can be counted. In some larvae the digestive tube is rather visible. It is interesting to note the présence of this species in the Ionian Sea, which extends the distribution of Pseudodistoma cyrnusense eastwards in the Mediterranean Sea. It was previously known in the western Mediterranean basin (Alboran Sea, Balearic Islands, Corsiea) whereas it lias now spread to the eastern part. This species is easily recognizable thanks to its smootli stomach and its pigmented spots on the thorax. The abundance of the species of the genus Pseudodistoma in the Mediterranean Sea, a genus which is rather rare in the rest of the world, should be given spécial notice. Aplidium hyalinum (Pérès, 1956) (Fie. 1, D) Loc. : Dred. n° 15, 114, 214, X 1. The colony which is greyish, transparent and soft has a gelatinous appearance. It adhères to a leaf of Posidonia. The colony shape is nearly conical. The size is 2 X 1 cm. At the base of the colony there is a bit of sand. The Systems are absent. Tlie zooids hâve an average length of 6 mm (fig. 1, D). The proportions between the thorax, the abdomen and the post-abdomen are : 1 : 2 : 3. 401 , 2 ASCIDIAN SPECIES NEW IN THE IONIAN SEA 979 The oral siphon has six lobes in a round shape whereas the atrial siphon, situated at the level of the third row of stigmata has a simple languet with variable size, according to the individnais. In the branchial sac there is an average of 12 rows of stigmata. The oesophagus is a bit longer than the stomach. The latter is more long than large (about 1.2 times) and shows five folds on its surface. The post-stomach forms a loop. The intestine is typical of the genus. The anus is situated at the level of the ninth row of stigmata. A post-abdomen, rather long, includes 4 to 6 male follicles arranged in a simple row below the ovary. In some individuals up to 11 male follicles hâve been counted. The ovary is far from the intestinal loop. The sperm duct is very clear. The presence of this species in the Ionian Sea extends the distribution of Aplidium hyalinum in the eastern Mediterranean Sea. It was unknown but for the description of Pérès (1956) starting from animais Corning from Tunisia. The species is not noticed in the western Mediterranean Sea (Banyuls-sur-mer, Mar¬ seille etc.). In 1958 Pérès already assumed tliat this species was endemic in the eastern Mediterranean. Phallusia ingeria Traustedt, 1883 (Fig. 2, A-C) Ascidia marioni Roule, 1884 : 240, pl. X, fig. 91, pl. XIII, lig. 126-127. Ascidia conchilega forme marioni Harant, 1931 : 81 ; Harant et Vernières, 1933 : 43. part Ascidia conchilega Salfi, 1931 : 330. Ascidia ingeria Monnict C. et Monniot F., 1971 : 1191, fig. 2, A. Loc. : Dred. n° 19. I hâve found only one specimen of this species. The general outer feature of this species reminds one of those of the genus Ascidia were it not for rnany minor openings of the neural gland which are typical of Phallusia genus. The specimen size is 3 cm long and 1,5 cm large. The colour is translucid white. The test is transparent, rather soft and shows some typical papillae on its surface, whereas there are neither epibionts nor sand nor débris. It has a basal fixation and its atrial siphon opens in the middle of its body. There are 45 filiform tentacles grouped in three sizes. The peripharyngial groove appears thin and straight, far from the very tiny dorsal tubercle which is C-shaped. The neural gland is about two and a lialf times its length away from the dorsal tubercle and it has several minor openings along its duct (fig. 2, B-C). The dorsal lamina edge appears as a double lamina for 1/10 of its length. Afterwards it is normal up to the entrance of the oesophagus, beyond which it becomes rather indis¬ tinct. The oesophagus opens at about 2/3 of its total length ; at this level the transverse bars on the right form big papillae which are sometimes lobed. The dorsal lamina disap- pears almost completely after its entrance into the oesophagus. The smooth endostyle is typical. Fig. 2. •— A-C, Phallusia ingeria Traustedt, 1883 : A, specimen without tunic opened by ventra branchial sac partly removed X 4 ; B, neural gland, with accessory openings ( X 27) ; C, detail of sory openings (x 100). D, Pseudodistoma cyrnusense Pérès, 1952 : colony of 5 cm high. ASCIDIAN SPECIES NEW IN THE IONIAN SEA 981 The branchial sac is not very thick ; there are 62 longitudinal bars on the right and 45 on the left. The minute plication is unremarkable. The branchial papillae on longi¬ tudinal bars at intersections with transverse bars are rather remarkable. The interme- diate papillae, when they exist, are much shorter (1/4 of the primary papillae). They are linked, but not ahvays, to the interstigmatic vessels. These vessels do not always appear. The longitudinal bars hâve the shape of a tube. There is a squaremeshed grid with four extended stigmata. In the front part of the body, there are about ten longi¬ tudinal bars on the right and three on the left end against the dorsal lamina. The straight oesophagus is nearly the same length as the stomach, which is ovoid. The intestine shows two closed loops ; the primary loop is situated at the same level as the atrial siphon, whereas, the secondary loop is at the stomach level. In both cases loops are very tight (fig. 2, A). The anus is at the same level as the intestinal loop and the atrial siphon. Unfortunately, the individual examined was completely immature. The rénal vesieles are large and limited to the stomach surface and do not appear on the intestine. Discussion The specimen examined corresponds undoubtedly to the one described by Traustedt (1883) in the gulf of Naples. The fact that it is a Phallusia is supported by the mimerons openings in the neural duct. On the contrary, the species described by Roule (1884) by the name of Ascidia marioni is probably the Phallusia ingeria ; actually the openings of the neural duct (which make a Phallusia of it), the size, the papillae on its test, the rénal vesieles, are also characteristic of Phallusia ingeria. Unfortunately, Roule does not give either a drawing or a description of the shape and position of the intestinal loop, which might hâve removed any doubts. So, I do not agréé either with Harant (1931) nor with Salfi (1933) who consider this species a form of Ascidia conchilega, which has some papillae on the right of the dorsal lamina that are completely absent here. The Ascidia ingeria described by Monniot C. and Monniot F. (1971) is in reality also a Phallusia ingeria (personal communication of the authors). Thus, the distribution of this species is as follows : Gulf of Naples (Traustedt), Northern Adriatic (Monniot and Monniot), Marseille (Roule, Harant), Sète (Harant), Atlantic coast of Morocco, Fedhala beach (personal communication of Monniot C. who examined some specimens collected by Liouville). Probably this species is more abundant than we think, but it has often been confused with Ascidia conchilega Müller, 1776, which resembles it closely, because of its intestinal loop, although it has a neural duct without any secondary openings. ASCIDIAN SPECIES NEW IN THE IONIAN SEA 983 Molgula rheophila (Pérès, 1956) (Fig- 3) Molgula impura Heller var. rheophila nov. var. Pérès, 1956. Loc. : Dr. 300, 377, 394. The test is fully coated hy sand shell. If débris is taken off, the dark grey colour of the test and little fibrils on it are visible. The size of the specimens examined is about 2 cm long, 1,5 cm high and 1,3 cm thick. The muscles are visible round the siphons and I hâve counted about 12 bands on the left and 12 on the right, both round the oral siphon and the atrial siphon. Particular spots are often visible in the inner part of the siphons ; they are not produced by a pigment, but, on the contrary, hy an optical phenomenon seen as blue-greenish spots of irridescence, such as those described by Monniot (1972) for Pyura munita (Van Name, 1902) and Pyura momus (Savigny, 1816). It is possible to count an average of 16 oral tentacles of three sizes. The oral tentacles of the first size are very long and reach the siphonal diameter. Three orders of ramification are présent mostly on the large ones, and two orders on others. The very marked peripharyngial groove has a typical feature : it cornes down to the level of the opening of the dorsal tubercle which is often located at a distance of about 2/5 of the intersiphonal distance. The opening of the dorsal tubercle is small, C-shaped. The dorsal lamina of course is shorter than usual, owing to the position of the dorsal tubercle and it is smooth and a bit shorter than the branchial folds. It enters the oeso- phagus directly. Six branchial folds are présent in the branchial sac which is not very thin. The markedness of the peripharyngial groove gives a particular feature to the branchial sac, since the first dorsal folds are very short as they are linked to the peripharyngial groove under the dorsal tubercle. The internai longitudinal vessels in a large adult were arranged as follows : Left : R. 1 (10) 1 (11) 1 (11) 1 (11) 1 (11) 1 (8) E ; Right : R. 1 (10) 1 (11) 1 (10) 1 (10) 1 (10) 1 (10) E. The folds do not overlap and it is possible to see the longitudinal bars of the fol- lowing folds. The longitudinal bars look like thin and short laminae. The branchial papillae are not visible. The stigmata are rather regular and infundibula are not seen. The oesophagus (fig. 3, A) is short and enters a stomach covered by a green liver with big papillae. The tubular intestine has the same dimensions up to the smooth anus. It is very interesting to note that the primary intestinal loop is not closed but forms an obtuse angle. The gonades (fig. 3, B) are also very typical. There are two of them and they are located on each side of the body. There is a big différence between them ; in fact, whereas the right gonad surrounds the rénal sac, the left one is situated in the secondary intestinal 984 ANGELO TURSI loop. It begins near the terminal portion of the gut and runs parallelto it, towards the ven¬ tral part of the body. In the middle of its length the left gonad turns at 90° and continues directly towards the atrial siphon. This feature is the same in ail the specimens examined. The male follicles are numerous and are situated in both sides of the elongate ovary. There is an inner sperm duct situated on the ovary, whereas the oviduct is found between the ovary and the mantle. The male and female papillae are long linked to each other and detached from the mantle. A little atrial vélum is présent. Discussion Up to now the specimens described by Traustedt (1883) and Monniot (1969), as Molgula occidentalis , by Heller (1877) as Molgula impura and by Pérès (1956), as Mol- gula impura var. rheophila, were categorised with the same spécifie nanie. Molgula occi¬ dentalis and Molgula impura are the same. On the contrary, Molgula rheophila which I describe here is separated from Molgula occidentalis owing to some features which I thought were enough to form a separate species. In fact, the left gonad has a very particular and constant feature and agréés perfectly with the descriptions given by Pérès (1956). Moreo- ver, as shown in figure by Pérès, the secondary intestinal loop is less closed than the one of Molgula occidentalis . Finally, the peripharyngial groove, forming a very deep fold at the level of the dorsal tubercle and the shortening of the dorsal lamina and of the dorsal folds, are characteristics as spécifie as the other ones. For this reason, I consider the variety of Pérès as a species with the following diagnosis : Molgula rheophila (Pérès, 1956) Molgula with six branchial folds on each side ; right. gonad S-shaped surrounding the end of the rénal sac ; left gonad, L-shaped, with posterior concavitv the distal part of which is not atta- ched to the rectum ; the branches of the intestine are not linked together during most of their path. The secondary intestinal loop, not very closed, takes the shape of an obtuse angle. The peripharyngial grove with the fold very deep at dorsal tubercle level is situated at about 2/5 of the iutersiphonal distance. The arrangement of the left gonad, L-shaped, with posterior concavity, is typical and is not présent in any other species of Molgula in the world with the right gonad surrounding the rénal sac. Conclusions So, the four species described are important for different reasons. Whereas for Mol¬ gula rheophila it is a matter of a description of a new species (although it is known by Pérès (1956) as a variety) for the other three species it is a matter of pointing out a disco- very, as they are very rare in the Mediterranean Sea. The importance of the discovery of the four species described once more emphasizes the necessity of a doser examination of the Ionian Sea, an examination which must be done above ail from the strictly systematical point of view. I think, in fact, that these four species of Ascidians are part of a greater number of rare species which should be disco- vered by the next survey in the Ionian Sea. ASCIDIAN SPECIES NEW IN THE IONIAN SEA 985 REFERENCES Cerruti, A., 1948. — Sui danni causati da alcuni Tunicati (Ascidie) aile coltivazioni di Molluschi del Mar Piccolo di Taranto. Breo. Communs Istituto Thalass., Taranto : 1-7. Gaill, F., 1972. — Répartition du genre Pseudodistoma (Tuniciers) : description de deux espèces nouvelles. Cah. Biol, mar., 13 : 37-47. Harant, H., 1931. — Contribution à l’histoire naturelle des Ascidies et de leurs parasites. Thèse, Paris. Harant, H., and P. Vernières, 1933. — Tuniciers. Faune de France, 27. Heller, C., 1877. — Untersuchungen über die Tunicaten der Adriatischen und Mittelmeers. Denkschr. K. Akad. IFiss., Wien, 37 : 241-272. Lafargue, F., and A. Tursi, 1975. — Contribution à la connaissance des Didemnidae (Ascidies Composées) des côtes de « Puglia » (Mer Ionienne et Mer Adriatique). Vie Milieu, 25 (IB). Michaelsen, W., 1924. — Ascidiae Krikobranchiae von Neuseeland, den Chatham und der Auck¬ land Inseln. Vidensk. Meddr. dansk. naturh. 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Tursi, A., 1971. — Primo contributo allô studio delle Ascidie del fondo a Cladophora di Porto Cesareo (Lecce). Thalassia Salentina, 5 : 31-38. — 1975. —- Ascidiacei delle coste tarantine. Oebalia (sous presse). 986 ANGELO TURSI Tursi, A., M. Gherardi and E. Lepore, 1974. — Andamento stagionale di alcuni Ascidiacei del Mar Piccolo di Taranto : dati preliminari. Memorie Biol. mar. Océanogr., 4 (4. 5, 6) : 421- 434. Tursi, A., M. Pastore and P. Panetta, 1974. — Aspetti ecologici del Mar Piccolo di Taranto : Ascidie, Crostacei Decapodi e Molluschi. Atti IV Simposio naz. Cons. Nat. Zool. Bari, 2 : 93-117. Van Name, W. G., 1945. — North and South American Ascidians. Bull. Am. Mus. nat. Hist., 84 : 1-476. Manuscrit déposé le 9 février 1976. Bull. Mus. natn. Hist. nat., Paris, 3 e sér., n° 401, sept.-oct. 1976, Zoologie 278 : 975-986. Achevé d’imprimer le 28 février 1977. 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