22 



dorsally curved apex. An embryonic shell (Fol) is often distinguished from the rest. The animal 

 has a ventral pallial cavity and a dorsal columellar muscle. The flexure of the intestine is 

 ventral. The anus situated on the left side; in the central nervous system the left portion 

 of the visceral mass is more develo]K-d than the right. 



The affinity of the Cavoliniidae with the Limacinidae has been discussed before. 



Three distinct genera can only be admitted among the various species, though formerly 

 a great number of generic titles has been used ^). 



These genera are: Clio, Ctivierina and Cavolinia. 



The genus Clio includes four subgenera : 



Creseis, Hyalocylix, Sly Ho la, Clio (s. sir.). 



Cuvierina was regarded by Gr.\y ") as a genus, representing a separate family ; however, 

 it clearly belongs to the Cavoliniidae. 



Cavolinia consists of two subgenera : 



\ Diacria, Cavolinia (s. sir.). 



According to Pelseneer, fourteen species of Clio ma)- be distinguished. However, I cannot 

 regard Clio conica as a distinct form, as I shall explain further on. xMuxthe has described a 

 new species of Clio (see note i), so that the number of species is fourteen. Six of them were 

 obtained by the Siboga. I cannot discuss the specific distinctness of the species which form the 

 subgenus Clio (s. sir.), as I could onl)- observe two species. 



As to the genus Cuvierina it includes only a single species. This species was represented 

 in the Siboga-material by a few empty shells only. 



The eight species of Cavolinia are all included in the .Siboga-collection. 



New forms have not been found. 



Clio Linne. 



1756. Clio Browne, The civil and natural History of Jamaica, p. 386. 



1767. Clio Linne, Systema naturae, ed. 12, vol. I, prt. 2, p. 1094. 



1 8 10. Cleodora Pcron and Lesueur, Histoire de la famille des Mollusques Pteropodes, Ann. 



iMus. HLst. Nat. Paris, vol. XV, p. 66. 

 1825. Styliola Lesueur, in: DE Blainville, Manuel de Malacologie, p. 655. 

 1828. Creseis Rang, Notice sur quelqucs Mollusques nouveaux appartenant au genre Cleodora, 



et etablissement et monographie du sous-genre Creseis, Ann. d. So. Nat. ser. i, 



vol. Xin, p. 302. 

 1837. Balantniin Benson, Notice on Balantiuiii, a Genus of the Pteropodous Mollusca, Journ. 



Asiat. .Soc. Bengal, vol. VL p- 151- 

 1875. Hyalocylix Yo\, Sur le developpement des Pteropodes, Arch. d. Zool. Exp., vol. IV, p. 177. 



Subgenus Creseis Rang (s. sir.). 



1828. Creseis (part.) Rang, Notice sur quelques Mollusques nouveaux, etc., Ann. d. Sc. Nat. 



ser. 1, vol. XIII, p. 302. 

 1828. Styliola (part.) Auctorum. 



1) As to the different generic names, see Telskneek, Chall. Rep. LXV, p. 41. 



2) Catalogue of the Mollusca in the collection of the British Museum. Prt. 11, I'teropoda, p. 23. 



