228 CONTRIBUTIONS TO CANADIAN PAL.IMNTOLOGY. 



in length. The specimens of 0. Amjelica figured by Professor Hall are 

 fi-om a little less than three quartoi-s to fully one inch in breadth. 



Athabasca Eiver, first ten miles below the Clear Water, and opposite 

 La Saline, about fifteen miles farther down the rivei-, Dr. R. Bell, 

 1882: four good specimens from the first of these localities and seven 

 from the second. 



AtHYRIS I'ARVULA. (N. Sp.) 

 Plate 32, ligs. 4, ,5 and 5a. 



Shell very small for the genus, moderately convex, varying in lateral 

 outline from transverselj' subelliptical to subcircular or longitudinally 

 and broadly subovate, in some specimens a little bi'oader than long, in 

 others the reverse: anterior margin distinctly sinuated. Ventral valve 

 more convex than the dorsal, its front margin depressed in the centre 

 in such a waj^ as to form a regularly concave mesial sinas which be- 

 comes obsolete at or near the midlength, its umbo prominent, tumid 

 and rather bj'oad, and its incurved beak truncated almost vertically 

 and perfoj'ated with a circular foramen. JDorsal valve with a mode- 

 rately elevated, rounded mesial fold on and near the front margin, its 

 beak being small, nan'ow and not very prominent. 



Surface marked with regulai'ly disposed, nearly equidistant and some- 

 what imbricating, concentric striations. Characters of the interior of 

 the valve unknown. 



The lai'gest specimen collected, a detacheil venti-al valve, is nine 

 millimetres and a half in lena-th, and ten mm. in its greatest breadth. 

 The dimensions of two other perfect specimens are as follows; — No. 1, 

 (tig. -i) maximum length, nine mm. ; greatest breadth, nine mm. and a 

 half (0.5); maximum thickness, six mm.; No. 2, (tigs. 5 and 5a) 

 length, eight mm. and a quarter (8.25) ; breadth, eight mm.; thickness, 

 five mm. and a half (5.5.) 



Athabasca Eiver, three miles below the Calumet (five good speci- 

 mens) and thirty miles below Red River (one perfect specimen), E. C. 

 McOonncll, 1890. 



This diminutive little species seems to be more nearly related to the 

 Athyris vittata of Hall than to the S. spiriferoides of Eaton, though it 

 may ptrove to be only a local diminutive race of the latter. As com- 

 pared with a series of authentic examples of A. vittata, from two locali- 

 ties in Iowa, recently forwarded by Prof. S. Calvin, the specimens col- 

 lected by Ml-. McConnell differ therefrom, not only in their much smal- 



