72 



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

 apoloj,ry for the insufficient manner in which T could trace out the innervation of the various 

 oro-ans. As to the ganglia and the nerves arising from them, I can, however, answer for the 

 accuracy of nn- description. 



When nothing else is noticed, the species studied is Pneuvwnoderma mediterraneiim. 



Family II. Clionopsidae. 



1S55. Clloidea (part.) Gegcnbaur, Untersuchungcn ubcr Pteropoden und Heteropoden, p. 212. 

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

 11, p. 613. 



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



1863. Clionacea (pnrt.) Troschel, Das Gebiss der Schnecken, Bd. 1, p. 54. 

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



1887. Clionopsidae Pelsenecr, Chall. Rep. LVIII, p. 33. 



1889. Cliopsidae Dall, in: Bullet. U. S. Nat. Mus., n" 37, 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 trace 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. I 



1855. Clio (part.) Gegenbaur, Untersuchungcn iiber Pteropoden und Heteropoden, p. 212. 

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



Up to the time of Bo.\s only one species was known. Bo.vs himself described a second 

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

 species further on. 



* I . Clionopsis grand is Boas. 



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



of the New Fngland 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 Bo.\s, this species has been recorded twice from the China Sea (2°4'X., 

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

 but it has not been found by the Siboga Expedition. 



