78 



Family IV. Clionidae. 



1840. Clionidae Gray, Synopsis of the contents of the British Museum, p. 86. 



1846. Clionoidae (part.) Agassiz, Nomenclator Zoologicus, Index, p. 90. 



1S50. Clioiieidae Gray, Catalogue of the Mollusca in the collection of the British Museum, 



prt. II, Pteropoda, p. 35. 

 1853. Pneitmodermidae (part.) d'Orbigny, in: Ramen de la Sagra, Histoire physique, politique 



et naturelle de l'ile de Cuba, Mollusques, vol. I, p. 70. 



1855. Clioidea (part.) Gegenbaur, Untersuchungen über Pteropoden und Heteropoden, p. 212. 



1856. Cliidae (part.) Woodward, A Manual of the Mollusca, p. 208. 

 1863. Clionacea (part.) Troschel, Das Gebiss der Schnecken, Bd. I, p. 54. 



As one knows. this family is characterised by the much elongated body, the absence 

 of a gill and by the cephaloconi, inserted at the outside of false Hps. It is very closely related 

 to the family of the Notobranchaeidae, but differs from it in the strongly pronounced tapering 

 of the body, the entire absence of a giil and by a median tooth in the radula. 



The foot of the Clionidae resembles much that of the Notobranchaeidae : the anterior 

 lobes have nearly the same shape, and no tubercle is found between them. The posterior lobe 

 of the foot, however, is still more reduced, and, as we shall see further on, it is even entirely 

 absent in the new genus Paraclioiic. 



Great confusion has existed for a long time in the systematic treatment of this family. 

 A rather large number of species, belonging to this family, and having been described nearly 

 alwaj's under the name of Clio, are insufficiently characterised, and the figures repre.senting 

 them are generally incomplete. Up to now, however, only one species is well known, viz. 

 Clione liviacina^ and it wouJd be very interesting to obtain further Information on forms 

 previously described, but never found again. I may, for the re.st, refer to Pelseneer ^) who 

 gave a critical systematical synopsis of this family. 



Now, to the genus Clione, I can add a new genus, procured by the Siboga Expedition. 



Clione Pallas. 



1773. Clio (part.) Phipps, A Voyage towards the North Pole, p. 195. 



1774. Clione Pallas, Spicilegia zoologica, fase. X, p. 28. 

 1776. Clio O. F. Muller, Faunae danicae prodromus, p. 226. 



1825. Cliodita (part.) Qoy et Gaimard, Description de cinq genres de Mollusques, Ann. d. 



Sci. Nat. sér. I, vol. V, p. 74. 

 1840. Spongiobranchea (part.) d'Orbigny, Voyage dans l'Amérique meridionale, vol. V, p. 132. 

 1852. Clio (part.) Rang, Histoire naturelle des Mollusques Ptéropodes, p. 77. 

 1855. Clio (part.) Gegenbaur, Untersuchungen über Pteropoden und Heteropoden, p. 212. 

 1855. Clio Auctorum. 



In Clione the body is much elongated, terminating into a rather thin point. The buccal 

 cones number from one to three pairs, the labial tentacles are well developed, and the posterior 



I) Chall. Kep. I.VIII, p. 41—51. 



