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Animal. Soft, furnished with a head, most fre- 

 quently with eyes and tentacula, or possessing 

 arms disposed in the form of a coronet. Body 

 sometimes naked, sometimes enclosing a shell, 

 hut generally having an external shell. 



>nly. 



l.PTEROPODA. 



Animal. Having 

 no feet, but 

 two opposite 

 fins, adapted to 

 swimming. 



Shell. Thin; car- 

 tilaginous, or 

 horny. 



Hyalaia, Clio (no 

 shell), Cleodor a, 

 Limacina, Cym- 

 bulia, Pneumo- 

 dermon (no 

 shell). 



2. GASTEROPODA. 



Animal. Foot united to 

 nearly the whole length 

 of the body, and used 

 for crawling. Body 

 straight, never spiral. 



Shell. Either cup-shaped, 

 or slightly rolled up ; in 

 some genera not cover- 

 ing the body. 



Eight Families. 



1. Tritonid;e. (No shell.) 



Glaucus, Eolis, Tri- 

 tonia, Scyllcea, Te- 

 thys, Doris. 



2. DentalidtE. (Shell 



tubular, open at both 

 ends.) Dentalium. 



3. Pryllididje. (Shell 



either of one cup- 

 shaped piece, or with 

 moveable pieces at 

 the back.) Phyllidea 

 (no shell), Chitonel- 

 lus, Chiton, Patella, 

 Siphonaria. 



4. Semiphyllididje. (Shell 



cup-shaped, but very 

 flat.) Pleurobranchus, 

 Umbrella. 



5. CalyptrjEIDjE. (Shell 



cup-shaped, though 

 irregularly so ; some 

 genera with internal 

 pieces.) Parmopho- 

 rus, Emarginula, 

 Fissurella, Crepidula, 

 Calyptnea, Hyppo- 

 nix, Pileopsis. 



6. BuLLiEiDjE. (Shell 



slightly rolled up.) 

 Acera (no shell), 

 Bullcea^ Bulla. 



7. AplysidjE. (Shell 



nearly flat and thin.) 

 Aplysia, Dolabella. 



8. LiMACiDiE. (Shell very 



slightly rolled or cup- 

 shaped.) Onchidium 

 (no shell), Limax, 

 Parmacella, Testa- 

 cella, Vitrina. 



frPODA 



Animal. Y\ 

 always ew 

 Shell. Spirfeet or 



ped in 



rts. 



y spiral, 

 Animal. Feev trans- 



either marin 

 Shell. Apertu 



, Colimacid^ 



The right \Atlan- 

 or tuYret&achea, 

 Helix, Ca 

 Clausilia, 

 Cyclostom 



. LYM1NLEID./E 



always sh? 

 orbis, Phy 



. MELANIDiE. 



lip sharp. | 

 . Peristomid 

 lips united 

 vata, Pah\ 



. NERITIDJE. 



left lip re 

 boat. Flu 



Una, Nerii 



. jANTHINIDjjj 



mouth trid 

 . Macrostom 

 very large' 

 Stomatell(\ 



. PLICACIDiEJ 



sharp. M 

 midella. 



. SCALARID-iEj 



touching, I 

 metus, Me\ 

 Delphinuli 



. TURBINIDiE.1 



midal, sul 

 mouth rou 



Solarium, 

 Planaxis, 



