40) I Hi: CHICAGO ACADEMY OF SCIENCES. 



rather wide, thick callus; inner lip narrow, reflected, nearly or quite 

 closing the umbilicus; the columella is inclined to be twisted and U 

 marked by a heavy plait. Some specimens are somewhat malleated. 



Length. 



Breadth. 



Ape 



rture length. 



Breadth. 





23.50 



9.50 





11.50 



4.80 mill. 



Cotype. 



22.00 



10.00 





11.50 



5.10 " 



" 



29.00 



12.50 







" 



(Baird.) 



15.50 



7.50 





7.60 



3.10 " 



Utah. 



17.00 



8.00 





8.50 



4.00 " 



tt 



Types: British Museum, London, England. 



Type Locality: Sumass Prairie, Frazer River, British Colum- 



bia. 



Animal, Jaw, Radula and Genitalia : Unknown. 



Range: British Columbia south to Northern Utah (41st parallel) ; 

 a species of the Columbian and Great Basin regions and of the Canad- 

 ian and Transition life zones. Sumassi doubtless occupies much of 

 the territory between the two records cited, but it has been confused 

 with palustris, jacksonensis and other western species and the records 

 cannot be relied upon. Only two lots have been seen which are authen- 

 tic, the type lot and one from Echo Canyon, Utah. 



RECORDS. 

 United States. 



Utah: Echo Canyon, Summit Co. (Hannibal). 

 British America. 



British Columbia : Sumass Prairie, Frazer River, New Westminster Dis- 

 trict (Baird; Lord). 



Geological Distribution : Unknown. 



Ecology : Not recorded. 



Remarks : Sumassi has long been a puzzle to most American 

 conchologists who have believed it to be a snyonym of palustris. The 

 original description is quite inadequate and in no wise differentiates the 

 species from palustris. Dr. Dall recently 1 quoted it as a variety of 

 catascopium, while the writer 2 referred certain fragile Lymnseas from 

 Lake George, near Florissant, Colorado, to it. Through the kindness 

 of Mr. E. A. Smith, of the British Museum, the writer was enabled 

 to examine and figure two specimens of sumassi from the original lot 

 collected by Mr. J. K. Lord. These specimens are quite different from 

 the Colorado specimens (which are a form of palustris) and show that 

 Dr. Dall was right in associating sumassi with catascopium. 



Sumassi closely resembles certain narrow forms of catascopium, 

 especially examples from the Great Lake region, but it is usually nar- 



^Alaska Moll., p. 78. 



2 Henderson, Moll, of Colorado, p. 180. 



