110 THE NAUTILUS. 



mode at 13, the skew strongly towards the smaller size, and the ex- 

 treme of large size barely overlapping the minimum size of porter a.* 



A few of the Canon Diablo thomsoniana have the mouth of the 

 shell very strongly contracted, so as to look like a distinct species, 

 but they are connected by intermediates with the ordinary form. 



Albinos have been found of both forms : 



A. thomsoniana mut. alba, nov. Canon Diablo, N. M., one. 



A. porter <z mut. alba, nov. Manzanares Valley, N. M., a few. 



At the monthly meeting of the Las Vegas Science Club, held 

 November 12, reported in Science December 27, 1901, p. 1009, the 

 authors exhibited a series of a supposed new species of AshmimeUa, 

 " proposed to be called Ashmimella autiqua, found fossil in the Pleis- 

 tocene beds of Las Vegas, N. M. It resembled in most respects A. 

 thomsoniana, but wholly lacked the parietal tooth." Upon further 

 examination it appears that the parietal callus has scaled off in the 

 specimens described, and it is likely that the shells are identical with 

 the living A. 



COLLECTING SHELLS IN MONTANA. 



BY MORTON J. ELROD, UNIV. OF MONTANA. 



[Continued from page 104-~\ 

 Limnsea stagnalis L., var. appressa Say. 



The first shells of this species were taken early in the year 1900 

 in a small pool along the Bitter Root river. A large spring supplies 

 the pool with clear, fresh water. In this pond a good series of both 

 living and dead shells was secured. A couple of dead shells were 

 found in Swan Lake in August, 1900. This is over a hundred miles 

 to the north of the Bitter Root locality, while water connection be- 

 tween the two places would be much more than double the distance. 



* A. porter x was taken the past summer at the head of Dailey Canon, in the 

 uppermost part of the Canadian Zone. The specimen is quite like the Beulah 

 ones. 



f A co-type of A. antiyi/a, received from Mr. Cockerell, bears out this conclu- 

 sion. It is without doubt A. t. porterse. The passage quoted above from 

 Science is the complete original account of antiqua. ED. 



