DAVENPORT ACADEMY OF NATURAL SCIENCES. 



corbicuijd^:. 



Genus Si'h.lrm.m Scopoli C 1 777}- 

 Sphserium uintaense, sp. nov. 



Shell thin, small, globose, ventricose, slightly 

 inequilateral, posterior and anterior margins well 

 rounded, very slightly produced posteriorly; ura- 

 bones large, subcalyculate, full, rounded, dark, 

 retaining embryonic shell, approximate ; basal 

 margin rounded, thus giving a circular outline to 

 shell; epidermis shining, dark straw or olive col- 

 ored, substriate, light yellowish on basal margin; 

 cardinal teeth microscopic, slightly in advance of 

 the middle region of the umbones, not widely 

 separating; lateral teeth small, short, somewhat 

 upcurved. 



Viewed in profile from in front, the point of junc- 

 tion of lower portion of valves with the embry- 

 onic shell appears as a well-marked obtuse angle. 

 Length, 4. 76 11 "" ; diameter, 4. o2 imn ; number of 

 specimens, eight. 



Habitat and Station. — A lake in the Uinta 

 Mountains, Utah, at an elevation of 10,500 feet. 

 The specimens were communicated by Prof. 

 ( >rson Howard, of Salt Lake City, and were 

 x 5 collected by him in August, 1885. 



This species is remarkable for its small size, all the specimens seen 

 being mature, and one with fry, and for the great elevation at which it 

 occurred. This is by far the greatest hypsometic range recorded for 

 any lamellibranch. The lake is snow-fed, and therefore its normal 

 temperature must be far below that of waters in which the Corbicu- 

 lidtz usually occur. Its extreme fragility and small size, it is believed, 

 must be coordinated with these features of its environment. Specimens 

 are in the collection of Prof. ( ). Howard and of the writer. 



It may not be altogether improper, in this connection, to advert to 

 the lax usage of naturalists in connection with the terms Jiabitat and 

 station. They are used as though strictly synonymic, while possessed 

 of a definite and precise meaning. It is proposed, therefore, that the 

 term habitat be used in the sense of geographic distribution, while sta- 

 tion should be used always and alone to indicate the immediate phys- 

 ical environment of the form considered. Such is the sense herein con- 

 templated. 



Fig. 4. 



Sl'll ERIUM UINTAENSE. 



