CONCHOLOGY. 87 



3. Genus Cleodora. PI. IX. 



Animal. Body oblong, gelatinous, contractile ; a head in front 

 with two wings, and the posterior part enveloped in a shell, head 

 distinct, projecting and round ; two eyes ; mouth in the form of a 

 small beak ; destitute of tentaculae ; two, opposite, membranaceous, 

 pellucid, and cordated wings, placed at the base of the neck. 



Shell. Pyramidal, triangular, of a gelatinous or cartilaginous 

 substance, very thin and transparent ; aperture obliquely trun- 

 cated. Inhabits the South American seas. Two species. 

 Cleodora pyramidata. Cleodora caudata. 



4. Genus Limacina. PI. IX. 



Animal. Body soft, oblong, two branchial fins situated at the 

 base of the neck; posterior part of the body spiral, and enveloped 

 in a shell. 



Shell. Thin, fragile, papyraceous, spiral, the whorls reunited 

 in a planorbis form, and deeply and largely umbilicated on one 

 side ; aperture large and entire. Inhabits the North seas. One 

 species. 



Limacina helicialis. 



5. Genus Cymbiilia. PI. IX. 



Animal. Body oblong, gelatinous, pellucid, enclosing a shell ; 

 head sessile ; two eyes, and two retractile tentacula ; mouth with 

 a retractile proboscis ; two, opposite, oblong, ovate, branched wings, 

 connate at their posterior base. 



Shell. Gelatinous, cartilaginous, very transparent, crystalline, 

 oblong, in shape of a shoe, from which it has derived the name 

 of the slipper, truncated at the summit ; aperture lateral and ante- 

 rior. Inhabits the Mediterranean. One species. 

 Cymbulia Peronii. 



6. Genus Pneumodermoii. PI. IX. 



A molluscous animal, without any testaceous covering, and 

 much resembling the genus Clio. Inhabits the Indian seas. One 

 species. 



Pneumodermon Peronii. 



