REPORT ON THE PTEROPODA. 



21 



but the larvae of Clione, as well as the adults of this genus, have always the posterior 

 extremity tapering and pointed, whereas that of Trichocyclus is round, as in Spongio- 

 branchsea. The locality where Trichocyclus dumerili was obtained (" Stidsee "), 1 also 

 agrees well with my interpretation. 



I have identified Cliodita caduceus 2 with Sp>ongiobranchsBa australis; because, in 

 spite of the imperfect figure given by Quoy and Gaimard, one can there recognise the 

 posterior gill of Spoiigiobranchsea, and the same constriction in the posterior half of the 

 body as in the specimens of Spongiobrarichtea austrcdis. The locality of Cliodita caduceus 

 (" entre l'ile de France et le Cap de Bonne Esperance") also agrees with this opinion. 



Pneumonoderma 3 Cuvier. 



1804. Pneumoderme, Cuvier, Meruoire concemant 1'animal de FHyale, &c, Ann. Mus. Hist. 



Nat. Paris, t. iv. p. 232. 

 1810. Pneumoderma, Peron and Lesueur, Histoire de la famille des Mollusques Pte'ropodes, &c, 



Ann. Mus. Hist. Nat. Paris, t. xv. p. 65. 

 1815. Pneumodermis, Oken, Lehrbuch der Zoologie, Bd. i. p. 326. 

 1815. JEgle, Oken, Lehrbuch der Zoologie, Bd. i. p. 326. 



1819. Pneumodennon, Lamarck, Histoire naturelle des animaux sans vertebres, t. vi. p. 293. 

 1846. Pneumonoderma, Agassiz, Nomenclator Zoologicus, Index, p. 299. 

 1855. Pneumouodermt/m, Herrmannsen, Indicis generum Malacozoorum primordia, vol. i. p. 309. 



Body ovate, rather long, a little shrunk behind, and rounded at its posterior 

 extremity ; visceral mass extending to that extremity. Skin pigmented, more coloured 

 on the right than on the left side (especially at the head). 



Head very long, or else united to the body by a long neck (this lengthening is a 

 consequence of the great length of the hook-sacs). 

 Labial tentacles short, and wide at their bases. 



Foot. — Posterior lobe long, always rounded at its 

 free extremity ; anterior lobes attached to the head 

 in their entire length ; between them there is a small 

 plicated tubercle, as in the Clionopsidse. 



Tlie Lateral Gill placed on the right side, is com- 

 posed of (1) three longitudinal, parallel crests, thin 

 and transparent, placed on the body wall; (2) a free ^^S^^mmS: 

 part, posterior to these crests, of a trianglar shape, L^IX^SVi's^^ crests; 3 ' 

 more or less elongate, of which the summit points 



backwards; the two free edges of this triangle bear crests which continue the lateral 

 somatic ones (see fig. 1, p. 6). The median somatic crest continues on the triangular 

 lobe (where it is very projecting) up to its summit. The two crests on the free sides 



1 Loo. cit, Oken, Isis, 1825, p. 735. 



2 Description de cinq genres de Mollusques, Ann. d. Sci. Nat., ser. 1, t. vi. p. 74, pi. ii. fig. 2. 



3 From 7rnvuau, lung, and h^», skin. 





