THE MOLLUSCA OF COLORADO 55 



Genus SPHAERIUM Scopoli 



Sphaerium near striatinum Lam. 



5. striatinum was recorded from Kremmling by Professor Cockerell (Nautilus, XX, 

 p. 21). I have since collected many dead shells from the same place, and they are not quite 

 typical. We have the same form from mouth of Sand Creek, on Bear River, Routt 

 County (Warren), from near Meeker (Bethel), from near Greeley (Beardsley), and I 

 recently collected 71 specimens alive from the Bear River just above Steamboat Springs. 



Genus CALYCULINA Clessin 



Calyculina near securis Prime. 



Specimens not quite typical (the same form as that recorded from Magnolia) have 

 been collected from a small lake between Gresham and Ward (S. A. Rohwer) at about 

 8,000 feet, associated, as at Magnolia, with Lymnaea (Galba) paluslris and Planorbis 

 exacuous. 



An undetermined species of this genus was found by Dr. G. S. Dodds at Sulphur 

 Springs. 



Genus PISIDIUM Pfeiffer 



Pisidium compressum Prime. 



I found a few specimens in Owen's Lake, east of Boulder. 

 Pisidium abditum huachucanum Pilsbry and Ferriss. 



A large number were found by Professor E. E. Hand, of Chicago, on the ranch of 

 G. W. Ames, at Evergreen, Jefferson County, and identified by Dr. V. Sterki. This is 

 an Arizona species described in 1906, in the Proceedings of the Academy of Natural Sciences 

 of Philadelphia, for that year, at page 173. It is interesting to find an Arizona species so 

 far north in the Rocky Mountains, as most of our known Colorado species came down 

 the range from the north, as pointed out by Pilsbry and Ferriss at page 150 of the paper 

 just cited. 

 Pisidium near roperi Sterki. 



This form is abundant at the head of Silver Lake, Boulder County, altitude about 

 10,000 feet. Dr. Sterki says it is not quite typical. It was described in The Nautilus, 

 Vol. XII, p. 77- 



We have undetermined Pisidia from a number of other localities. The distribution 

 of the various species in Colorado is as yet very little known. 



GASTROPODA 



Genus OREOHELIX Pilsbry 



The genus Oreohelix includes the largest land snails of Colorado. A number of 

 species have been found in enormous numbers at many localities and much interesting 

 information obtained as to habitat, distribution, etc. We omit all but the meic locality 

 records from this paper, because a rather extended report has just appeared [The 

 Nautilus, Vol. XXV, pp. 133-139; Vol. XXVI, pp. 9-11, 1912]. 

 Oreohelix strigosa depressa Cockerell. 



