[10] 



§§ Shell ohlong or oval. 

 Family Orthalicidje. 



Tropical, a few species inhabiting tlie Gulf States. 

 §§§ Shell cylindrical or pupseform. 

 Family Pupad^. 



Distribution universal. 



ft Shell internal, rudimentary, contained beneath the 

 'mantle. 



§ Shell small, flattened^ not spiral. Respiratory orifice 

 in the p)Osterior right margin of the ma7itle. 



Family Limacidje. 



Distributed tlirougliout the States east of tbe Rocky Moun- 

 tains, and one species in Oregon. Most of tlie 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 

 gramdes. liesjnratory orifice in the anterior of tlie 

 right margin of the mantle. 



Family Arionid^. 



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

 ern States. 



ftt Shell entirely absent. Mantle covering the entire 

 upper surface of the body of the animal. 



Family PhilomyceniDxE. 



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, coinaceous. 



Family Veronicellid^. * 



Tropical. One species only occurs in Florida. 



§§ Mantle tubercidate. 



Family OnchidiidyE. 



A single species is found in Lower California. 



