83 



Rad ui a: with a median looth, which carrics a ratlicr long spine, directed distally 

 (fig. 1^1 A). The fonnula is 3. i .3; the lateral teeth present a slender shape. 



Mook-sacs: short, as in Clioiic\ the hooks have a broad base, and are bent abruptly 

 at their extremity (fig. 1 5 i B). 



J a \v : absent. 



Length: the largest specimen measures 3 mm. 



Colour: greyish or yellowish ; the chromatophors are black (spirit-preservationj. 



Re mark: though the animals are very small, they are no larvae, as no tracé of 

 ciliated rings exists. 



A n a t o m i c a 1 R e m a r k s. 



By making a series of transverse sections through one specimen, I have convinced 

 myself that the anatomy of the onh' representative of this new genus is very much like that 

 of Clione. The digestive tract does not offer anything remarkable. The anus opens at the 

 ventral margin of a cloacal depression; at the dorsal margin the osphradium is situated. 

 The kidney opens immediately beneath this organ. A penis is entirely absent; perhaps this is 

 another peculiarity of the genus. The gonad is situated ventrally to the liver; a thin efferent 

 duet without any perceptible swelling in its course opens into the muciparous and albuminiparous 

 ti^lands, the folds of which consist of a high cylindrical epithelium. A vas deferens with a small 

 hernia at its base, opens beneath the distal margin of the right fin. The gonad itself is made 

 up of numerous rounded cells, consisting chiefly of a nucleus and probably spermatids. Some 

 ova with very large nucleus are found at the periphery. 



The central nervous system is arranged in the same manner as in Clione. The pedal 

 ganglia possess a long commissure too. 



Family V. Halopsvchidae. 



1850. Cymbiiliadac (part.) Gray, Catalogue of the Mollusca in the collection of the British 



Museum, prt. II, Pteropoda, p. 24. 

 1856. Hyaleidae (part.) Woodward, A Manual of the Mollusca, p. 204. 

 1859. Eurybidae Chenu, Manuel de Conchyliologie, vol. I, p. 115- 

 1863. Eiiribiacca Troschel, Das Gebiss der Schnecken, Bd. 1, p. 54. 

 1887. Eurybiidae Fischer, Manuel de Conchyliologie, p. 426. 

 1887. Halopsychidae Pelseneer, Chall. Rep., LVIII, p. 52. 

 1887. Cyvibuliidae (part.) Auctorum. 



Among the Gymnosomata the Halopsychidae take an isolated place. Though they 

 are certainly related to the Clionidae, there is a remarkable distance between these families. 

 Indeed, the general aspect of the only representative of the Halopsychidae, sufficiently known, 

 only vaguely suggests the common habitus of the Gymnosomata ; and it is only by means 

 of more careful examination, that the general characters can be discovered. One can even 



