8o KANSAS UNIVERSITY QUARTERLY. 



Europe is altogether wanting in India. A name given to a shell is 

 simply a means of conveying to other fellow workers a concrete 

 idea of what is meant, and this purpose is not gained if v/e unite 

 too many different forms under one name." 



Meek seems to be very much of the same mind for he says, 

 speaking of a shell of this genus, "It is not sufficient, however, 

 for specific identification (speaking of the specimen in hand) 

 though it would not be difficult for those whose method of making 

 palaeontology easy leads them to include, under the single species, 

 speliincaria, all the known forms of this group, to see that species 

 in it."* There is a considerable truth in these statements, but to 

 decide where to draw the line in the present case is none the less 

 difficidt. 



Some of the American shells of this genus are about as puzzling 

 as those of Europe. Not only are the variations found in the same 

 formation here as there, but, to add to the complications, some of 

 the varieties are found commingled throughout fifteen hundred to 

 two thousand feet, or more, of heavy limestones and shales. In 

 one group it seems that all the apparently hap-hazard variations 

 are as persistent as the general form. 



It would seem that in a form with so many variations and having 

 such a great stratigraphic range, certain extreme characters could 

 be selected and separated in to varieties coextensive with each 

 other. This was attempted repeatedly but always failed. Of this 

 group, hereinafter referred to as P. cf. /lawni, we have over two 

 hundred specimens from the upper Coal Measures at Turner,- Kan- 

 sas. In attempting to separate diverse forms, before getting nearly 

 through with the specimens a point is always reached where it is 

 impossible to determine to which form a large number of speci- 

 mens belong, as they they seem to possess equally the characters 

 of both. This was equally true, no matter what the character of 

 the features selected. 



Mr. Shuchert thinks that Meek's /'. hawiii var. (n'lita is not vari- 

 etally distinct from that species and I am inclined to agree with 

 him on that point. 



Following are the descriptions of three new forms referred to of 

 this genus which, I think, are sufficiently distinct to be very easily 

 recognized, especially the first two. I am not clearly satisfied as 

 to whether their characters are of specific or varietal importance, 

 though I think that the first two will prove to be specifically 

 distinct and the third a variety of P. liawni Meek. The first two 



*I*Mi). Rep. r. S. Geol. Siir\ . Neb., p. 2(10. 



