78 



Fainil) I\'. Clionidae. 



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



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



1850. Clioneidae Gray, Catalogue of the Mollusca in the collection of the British Museum, 



prt. II, Pteropoda, p. 35. 

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



et naturelle de Tile de Cuba, MoIIusques, vol. I, p. 70. 



1855. Clioidea (part.) Gegenbaur, Untersuchungen Liber 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 o-ill and by the cephaloconi, inserted at the outside of false lips. 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 gill 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 shajje, 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 o-enus Paraclionc. 



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

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

 always under the name of Clio, are insufficiently characterised, and the figures representing 

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

 Clione liniacina, and it would 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 sj'nopsis 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, fasc. X, p. 28. 

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



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



Sci. Nat. ser. I, \-ol. V, p. 74. 

 1840. Spongiobranchea {part.) d"Orbigny, Voyage dans PAmcrique meridionale, vol. V, p. 132. 

 1852. Clio {part.) Rang, Histoire naturelle des MoIIusques Pteropodes, p. Jf. 

 185;. Clio (part.) Gegenbaur, Untersuchungen iiber Pteropoden und Heteropoden, p. 212. 

 1855. Clio Auctorum. 



In Clioiic 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) CluiU. Kcp. LVIII, p. 41 — 51. 



