2 LAND AND FRESH-WATER SHELLS OF N. A. [PART I. 



Operculum neve^ present in the adult. Animal usually ter- 

 restrial. 



I have adopted the systematic classification of the Geophila 

 proposed by Dr. J. E. Gray, which seems to express more satis- 

 factorily than that of others, their natural systematic arrangement. 

 Its general characters are as follows : — 



A. Head, eye-peduncle, and tentacles retractile under the skin. 



Sect. 1. Vermivora. Buccal mass very large, elongate, projectile like a 



proboscis. Jaw none ; teeth numerous, slender, conical, distant. 



Mantle well defined. Subterraneous ; carnivorous, or worm-eating. 

 Sect. 2. Phyllovora. The buccal mass small, ovoid, not produced. .Jaw 



distinct, horny ;' teeth numerous, four-sided, close together on the 



lingual membrane. Herbivorous. 



B. Head, eye-peduncle, and tentacles simple, contractile. 



I use these subdivisions because I believe they exist in nature, 

 and with the same understanding do I use the divisions of families 

 and genera. The subgenera which I adopt in the following 

 pages I consider merely artificial divisions, used for convenience 

 in dealing with genera abounding in numerous species. 



It will be seen that I have usually adopted for the larger 

 divisions the descriptions given by H. & A. Adams — for genera 

 and subgenera those of Albers and Martens. From the last 

 named I have also usually adopted the subgeneric names, without 

 inquiry into their precedence, having neither time nor inclination 

 to attempt myself to disentangle the confused synonymy. 



In the synonymy of the species I have quoted only authors 

 giving a description or figure. I have personally consulted all 

 the references, unless otherwise specified. 



The subject is brought down to January, 1868. 



Habits, &c. — -They live mostly in the forest, sheltered under 

 the trunks of fallen trees, layers of decaying leaves, stones, or in 

 the soil itself. I.u these situations they pass the greater part of 

 their lives. In the early days of spring, they sometimes assemble 

 in considerable numbers, in warm and sunny situations, where 

 they pass hours in indolent enjoyment of the warmth and ani- 



' Except in Cylindrclla. 



