Some Notes on American Land Shells. 35 



overlying the sutures. Instead, the latter are impressed and well de- 

 fined. The lower surface is marked with elongated pits or scars, with 

 their longer axis radiating from the base of the columellar depression, 

 which are entirely wanting in H. spinosa. 



The latter has the under surface thicklj^ crowded with plainly seen 

 microscopic revolving lines. They exist, also, on the H. edgariana, 

 but are much smaller, and not easily seen unless with a good magni- 

 fier. The upper surface of the shells is very much alike, except that 

 the prostrate hairs are more crowded in edgariana. The animal is 

 black, very active, and carries the shell balanced horizontallj^ Not- 

 withstanding the diverse characters of these species, they seem to be as 

 closely united as the tj^pical II. (Patida) alternata, and H, [Patula) 

 mordax, inhabiting the same region, and iu the same stations, and 

 which have been made synon\mious. 



H. [Stenotrema) labi'osa, Bland. — I have received this rare species 

 from two localities, Springfield, Mo., and Hematite, Mo. At the former 

 localit}^ it was associated with the equally rare H. [Folygyra) jacksoni^ 

 Bland; at the latter w^itli the II. [Polygyra) dorfeailliana., Lea, a 

 species which is far from common. The force of the remark under 

 this species in Terrestrial MoUusks, vol. v., is hardly apparent, "the 

 thickened and reflected peristome, and deep wide notch, sufficiently- 

 distinguish lahrosa from edgariana^^'' as there is no reason whatever 

 for confounding these species. This shell belongs to that division of 

 the group represented by stenotrema and hirsuta, and not to that 

 formed b^^ spinosa and edgariana. The shells brought together bv 

 Mr. Binney, in the volume above referred to, under the genus Steno- 

 trema of Rafinesque, are readil}^ arranged in four groups. First, the 

 group including edvardsi and barbigera characterized by the extraor- 

 dinary development of the epidermal hairs. Second, that formed by 

 spinosa and edgariana equall}^ well characterized by the sharp pe- 

 riphery of the body-whorl, and the prostrate epidermal hairs. Third, 

 the group containing hirsuta, stenotrema., labrosa and maxillata, in 

 which the epidermal processes are shorter, and the surface is more tu- 

 berculate; and lastly the group containing monodon^fraterna, leaii and 

 germana. Among themselves the species in each group are united 

 more or less closelj^, those of the monodon group being usually regard- 

 ed as varieties of that shell, with the exception of H, germana^ which 

 Mr. Binne}' finds to be related to Stenotrema by its jaw and dentition, 

 and more nearly to 3Iesodon by its shell; a prominent character of 

 which is the want of the internal tubercle. The writer may here re- 

 cord his opinion, that H. leaii is also a valid species if other species 



