THE 
AMERICAN NATURALIST. 
VoL. xvii. SEPTEMBER, 1884.—No. 9. 
NOTES ON A NEVADA SHELL (PYRGULA 
NEVADENSIS). 
BY R. ELLSWORTH CALL AND C. E. BEECHER. 
4 PS form was described by Dr. R. E. C. Stearns! from mate- 
rial furnished in part by one of the present writers. The 
description was based upon the external characters presented by 
the shell alone, for at that time material containing soft parts had 
not been discovered. Since the printing of the description 
Opportunities were afforded us to make extensive collections of 
recent and Quaternary shells in the Great Basin, and the biologic 
_ 4nd climatologic results of our study are now being formu- 
__ lated for publication under the auspices of the United States Geo- 
logical Survey. l 
= _ The examinations made along the south and west shores of ~ 
Pyramid lake, Nevada, demonstrated the existence of this form, 
: la, in countless thousands in that remarkable body of water. 
Ata single locality more than a gallon was obtained, associated 
vith many hundreds of Pompholyx effusa Lea, and many Physa 
humerosa Gould. From this material a large number of speci- 
mens, containing the dried animals, was assorted and sent to Mr. 
Beecher, who has successfully worked out the dentition, and 
__ “Seribed it as below 3 
Pc The genus Pyrgula has not received a uniform treatment at the 
hands of Systematists, none of whom have yet studied the denti- 
_ ‘Proc, Phil g i re. 
tions be i a a ke r pile as here given. His work is 
os and painstaking, and we hope jointly to present, in the course of time, 
_ Nery much more of his careful work in dentitions. 
_ VOL, XVEIL—No. 1x, 54 
