212 ^ WEST AMEKICAN SHELLS — STEARNS. 



The occurrence of the above iu the region where Mr. Henshaw found 

 it is not simply interesting in itself, through adding a new locality as 

 well as a new species to what was previously known, but the altitude of 

 Eagle Lake, 5,115 feet above the sea, being considered, is an important 

 point in the matter of the hypsometrical distribution of the group to 

 which the form herein- described is allied, and is, so far as I can learn, 

 the highest elevation at which any American species has as yet been 

 detected, Thecharacterof the habitat is in another aspect peculiar. The 

 basin of the lake, according to Mr. Henshaw, is composed of a dark- 

 colored lava or scoriaceous matter, and the color of the shell, it would 

 seem, is quite in harmony with this feature of its environment. 



As to the generic and malacological relations of those West American 

 forms which Mr. Tryon has included in his monograph of the Strepoma- 

 tidw, but little, if anything, is known. Whether their proper place is 

 with the true Melanians or with the East ]!^orth American Goniohasis 

 remains to be shown. It may be found that they constitute, and upon 

 reasonably satisfactory characters, a separate though collateral group. 

 The species above described is therefore placed here provisionally. 



Family Capulid^. 



Genus CAPULUS. 



Cyclothyca, Subgenus nov. 



Shell small, spiral, few whorled ; spire short, and body whorl large 

 and transversely elongated or produced. Aperture oblong, ovate, more 

 or less oblique, very large, continuous and effuse. Surface spirally 

 ribbed and marked with longitudinal growth lines. Example C. cor- 

 rugata as follows : 



Cyclothyca coirugata sp. nov. 



Plate XV, Figs. 5, 10. 



Shell subspiral, transversely much elongated or produced ; number 

 of whorls two to two and a half, rapidly enlarging. Apex rounded, 

 smooth or nearly so, subvitreous and shiny. Aperture ovate, effuse 

 and continuous, obliquely expanded and much prolonged. Surface of 

 principal whorl ornamented with ten to fifteen revolving ribs, of which 

 the upper or principal ones, seven or eight in number, are the more 

 prominent ; otherwise sculptured by more or less conspicuous subsidi- 

 ary longitudinal growth lines. Sometimes the main ribs, which are 

 broadly channeled between, show slight imbrications, and in one of the 

 specimens the longitudinal growth lines, though secondary to the re- 

 volving ribs in prominence, are conspicuously developed and cancellate 

 the sculpture. The apex also varies iu prominence ; in the example 

 figured it is quite elevated, iu another it is nearly appressed to the line 

 of the body whorl. The outer lip is ribbed internally corresponding to 



