GASTEROPODA PULMONEA. 



their branchiae are attached under the margin of their mantle, as in 

 the Inferobranchiata(a). 



ORDER I. 

 PULMONEA*. 



Tlu- Piilinoiiia arc distinguished from tin* otlu-r Moiluscaby respiring 

 tla^tio air tlirouerh a hole opening under the margin of the mantle, 

 and which they dilate and contract at will ; and accordingly have no 





* M. de Blainville prefers the term Pulmonobranchiata. 

 (n) The Gasteropodes form, in Lamarck's classification, the Second Order 

 TWELFTH CLASS. 



MOLLUSCA. 



tinier II. Les Gatttropodes. 



:ii;ils with the body straight, never in a spiral form,, nor enveloped in a shell 

 capable of containing the whole of it ; they have beneath the belly a foot or muscular 

 dNk, united nearly to the whole length of the body, and serving them to crawl with. 

 Some are naked, others are screened by a dorsal shell, not sheathed in the body ; 

 and others again, have a shell more or less concealed in their mantle. 

 First Section. Les Hydrobranchia. 

 ANIMALS only breathing water. 



TThe respiratory organs, in what- 

 Genus Glaucus 

 .... Eolis 



---- Tritonia ...... First Family. 



.... Scyllaea ...... Les Tritoniens. 



.... Tethys 



.... Doris 



Phyllidhi 

 Chitonellus 

 Chiton 

 Patella 



lus' ' .' ] 1 



Pleurobrancans. 

 Umbrella. . . . 



ophora .. ' 

 .rinula . . 

 Fttturella .... 



>triea 



!ula 



Third Family. 

 Les Seraiphyllidiens. 



Fourth Family. 

 Les Calyptraciens. 



Fifth Family. 

 Bulleens. 



ever part they are situated, 

 ! are always elevated, either 

 ;' in filets, laminae, tufts, or 

 \ like a comb ; they are placed 

 I above the mantle, either on 



the back or on the sides, and 

 L not in any particular cavity. 



r Respiratory organs placed be- 

 neath the border or edge 

 of the mantle, and disposed 

 in a longitudinal series round 

 the body, or on one side, not 

 being placed in any particular 

 L cavity. 



{Gills as above, but placed on 

 the right side of the body 

 only. 



r Respiratory organs placed in a 

 cavity appropriated to them 

 on the back of the animal, 

 I near the neck, projecting 

 | cither within the cavity or 

 above it. Shell always exter- 

 nal and covering the animal, 

 L which is without tentaculae. 

 Gills placed in a particular ca- 

 vity near the posterior part 

 of the back, and covered by 

 the mantle or by an opercu- 

 lary shield. No tentaculae. 



