72 



Finally I wish to remark, that the absence of well-preserved material may be my only 

 apology for the insufficiënt manner in which I could tracé out the innervation of the various 

 orcans. As to the eang-lia and the nerves arisin»- from them, I can, however, answer for the 

 accuracy of my description. 



When nothing else is noticed, the species studied is Pnciiuionodcnna incdiierra7ieiini. 



Family II. Clionopsidae. 



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

 1859. Pneiivioderiuonidae (part.) H. and A. Adams, The Genera of recent Mollusca, vol. 

 II, p. 613. 



1862. Clionidae (part.) Bronn, Die Klassen und Ordnungen des Thierreichs, Bd. III (2), p. 645. 



1863. Clionacca^lpart.) Troschel, Das Gebiss der Schnecken, Bd. I, p. 54. 

 1873. Cliiiopsidci Costa, Pteropodi deila Fauna di Napoli, p. 24. 



1887. Clionopsidae Pelseneer, Chall. Rep. LVIII, p. ■},i. 



18S9. Cliopsidae Dall, in: Bullet. U. S. Nat. Mus., n" ij , p. 82. 



The characters of this family consist chiefly in a very long retractile proboscis, without 

 buccal appendages, a quadrangular posterior gill, while the lateral one has disappeared. 



A specimen, caught by the Siboga Expedition did not exhibit, however, any tracé of 

 a posterior gill. 



Only one genus is known. 



Clionopsis Troschel. 



1854. Cliopsis Troschel, Beitrage zur Kenntniss der Pteropoden, Arch. f. Naturgesch., Jahrg. 



XX (i), p. 222. 

 1S55. Clio (part.) Gegenbaur, Untersuchungen über Pteropoden und Heteropoden, p. 212. 

 1862. Clionopsis Bronn, Die Klassen und Ordnungen des Thierreichs, Bd. 111(2), p. 645. 



Up to the time of Boas only one species was known. Boas himself described a second 

 species; and a third one was procured by the Challenger Expedition. I shall describe a new 

 species further on. 



*i. Cliotiopsis grandis Boas. 



1885. Fneumodervion pcronii Verrill, Third Catalogue of the Mollusca, added to the Fauna 



of the New England Coast, Transact. connect. Ac. Arts and Sci., vol. VI, p. 431. 



1886. Cliopsis grandis Boas, Spolia atlantica, K. dansk. Vidensk. Selsk. Skriv., 6 Raekke, 



Bd. IV, p. 170. 



1888. Clionopsis grandis Pelseneer, Chall. Rep. LVIII, p. 136, pi. II, figs. 7 — 8. 



According to Boas, this species has been recorded twice from the China Sea (2°4'X., 

 106° 50' E. and 3°3o'N., 107° E.). Very probably it occurs in the East-Indian Archipelago, 

 but it has not been found by the Siboga Expedition. 



