171 



Clio. This genus has no shell. 

 C. borealis, C. australis. 



Cleodora. Shell gelatinous, cartilaginous, transparent, in shape of a 

 reversed pyramid, or lanceolate, truncated and open at the summit. 

 C. pyramidata, C. caudata. 



Limaoina. Shell thin, fragile, papyraceous, spiral; the whorls reunited in 

 a discordal manner, like the planorbis. 

 L. helicialis. 



Cymbulea. Shell gelatinous, cartilaginous, very transparent, crystalline, 

 oblong, in shape of a shoe, truncated at the summit; aperture lateral and an- 

 terior. 



C. Perronii. 



Pheumodermon. This genus has no shell. 

 P. Perronii. 



ORDER II. GASTEROPODA. 



Some are naked, others have a dorsal shell, not enveloping; again, others 

 have a shell more or less hidden in their mantle. 



This order is divided into two sectons — Hydrobranchia, and Pneumo- 

 branchia. 



SECTION I. HYDROBRANCHIA 



Contains six families, viz. Tritonia, Phyllidiana, Semi-Phyllidiana, Calyp- 

 traciana, Bullaeana, and Aplysiana. 



TRITONIA.— Six Genera. 



Without shells, either external or internal. 



Glaucus. No shell. 



Eolis. Do. 



Tritonia. Do. 



Scyll^ea. Do. 



Tethys. Do. 



Doris. Do. 



