OF CONCIIOLOGY. 223 



§§ Shell ohlong or oval. 



Family Orthalicid^. 



Tropical, a few species inhabiting the Gulf States. 



§§§ Shell cylindrical or im]^seform. 



Family PuPAD^. 



Distribution universal. 



ft Shell internal, rudimentary, contained beneath the 

 tnantle. 



§ Shell small, flattened, not spiral. Respiratory orifice 

 in the p)Osterior right r)iargin of the mantle. 



Family Limacid^. 



Distributed throughout the States east of the Rocky Moun- 

 tains, and one species in Oregon. Most of the species are 

 European in origin, and only occur near the coast, especially 

 in the vicinity of the large commercial cities. 



§§ Shell represented only hy a few agglomerated calcareous 

 granules. Respiratory orifice in the anterior of the 

 right margin of the ma7itle. 



Family Arionid^. 



A single European species is found in seaports of the North- 

 ern States. 



ftt Shell entirely cdisent. Mantle covering the entire 

 tipper surface of the body of the animal. 



Family Philomycenid^. 



There are two species known, which inhabit the Northern 

 and Middle States. 



** Tentacles (and head) contractile beneath 



THE mantle, which COMPLETELY COVERS THE BODY 

 OF THE ANIMAL. 



§ Mantle smooth, coriaceous. 

 Family VERONiCELLiDiE. 



Tropical. One species only occurs in Florida. 

 §§ Mantle tuberculate. 

 Family ONCHiDiiDiE. 



A single species is found in Lower California. 



