THE OTTAWA t(ATURALIST. 



Vol. XVI. OTTAWA, MARCH, 1903. No. 12. 



DESCRIPTION OF A FOSSIL CYRENA FROM ALBERTA. 



By J. F. Whiteaves.* 

 (With one plate.) 



In 1888, Mr. T. C. Weston, of the Geological Survey Depart- 

 ment, made an interestinij collection of fossils from the rocks 

 exposed at Fossil Coulee, Milk River Ridge, in southern Alberta. 

 According to Dr. G. M. Dawson, the plateau through which this 

 coulee is cut is capped by the Pierre shales, and the section in the 

 coulee itself " may be regarded as a representative one of the 

 upper or pale portion of the Belly River series."! The species 

 represented in this collection are apparently as follows : Ano- 

 donta propatoris. White, several good specimens; Unio, three un- 

 described species, one very large ; Cyrena a large and previously 

 undescribed species ; Physa Copei, White, the short spired typical 

 form ; Goniobasis, two species ; all purely fresh-water forms : and 

 a land shell, like Anchistoma parvulum. The Cyrena in this 

 collection may be thus named and described : 



Cyrena Albertensis, sp. nov. 



Shell quite large for the genus, moderately convex, ovately 

 subtrigonal in marginal outline, a little longer than high, and very 

 inequilateral. 



Anterior side short, rounded ; posterior side longerand more 

 pointed, most produced in the postero-basal region, the posterior 

 extremity being subtruncate rather obliquely above and narrowly 



* Communicated by permission of tlie Acting: Director of the Geolog-ical 

 Survey. 



t Geolog-icul Survey of Canada, Report of Progress for 1882-83-84, 

 pp. 50 and siC. 



