416 PROCEEDINGS OF THE ACADEMY OP [1889. 



So far, it has not been possible to examine the soft parts and thus 

 complete our knowledge and description of the species ; but it is to 

 be expected that the necessary fresh, if possible living specimens 

 will be found, and I hereby would invite the active collectors of the 

 north-western states to look especially for this Pupa, in order not 

 only to make a complete examination, but also to know more about 

 its geographical distribution, and possible variation. 



As already stated, our species ranges with P. armifera and P. 

 contractu Say, standing nearer the latter. Yet it is different from 

 this species by the shape of the aperture, the wanting callus 1 con- 

 necting the margins on the body-whorl, by the longer crest behind 

 the aperture, which in contracta disappears in about the middle of 

 the (height of the) whorl, and by the wanting constriction, especially 

 in the columellar wall, not to speak of the size and shape of the 

 whole shell. The lamelke also show some marked differences, such 

 as the presence of a high basal, the shorter columellar not reaching 

 the base, but with relatively larger horizontal part, the bifurcation 

 of the parietal and the presence of a supra-palatal, the last just as it 

 is in P. armifera. 



It must be added here that the specimen first obtained from 

 Minnesota in several respects differs from those found in Illinois 

 and Iowa, which I consider as typical, by its size which is \ smaller, 

 by the basal lamella developed in a peculiar way, being rather 

 longer at the truncated top than at its foot, and by the stronger, 

 thicker palatal lamella?. Yet, as there was only one specimen, 

 it is likely to be an individual peculiarity ; even then, of interest. 

 Should, however, more specimens be found with the same configura- 

 tion, they would represent a distinct and well-characterized variety ; 

 possibly it is a peculiar northern form. 



1 In many specimens of P. contracta so strongly developed, that the peristome 

 is rendered continuous. 



