WHiTEAVES.] LARAMIE AND CRETACEOUS INVERTEBRATA. 3 



Out the only fossils collected are a few casts of a Unio which are not 

 sufficiently perfect to be identified. A few fragments of Unios and 

 other fresh water shells were noticed at some other localities, but no 

 specimens were collected. 



The supposed new species of Unio from near the mouth of the Old 

 Man Eiver may be described as follows : 



Unio Albertensis. (N. Sp.) 

 Plate 1, fig. 1. 



Shell very inequilateral, strongly compressed at the sides and 

 thickest near the mid-length, so that the outline of the closed valves as 

 seen from above is regularly lanceolate : lateral outline transversely 

 subelliptical : length about twice the maximum height : height almost 

 exactly twice the greatest thickness. Anterior and posterior extre- 

 mities both rounded at the margin, and of nearly equal breadth : an- 

 terior side very short : posterior side considerably elongated, about 

 three times as long as the anterior : ventral margin and superior bor- 

 der almost straight and nearly parallel for the greater part of their 

 length, — the former rounding upwards obliquely and rather ubi'uptly, 

 and the latter sloping downwards in an equally abrupt and obliquely 

 convex curve, at each end. Beaks very small and inconspicuous, 

 placed about half way between the centre and the anterior termination 

 of the valves. 



Surface concentrically striated : test rather thin : characters of 

 the interior unknown. 



Length, seventy millimetres : maximum height, thirty-six mm. : 

 greatest thickness, eighteen mm. 



Upper Belly Eiver, Alberta, N. "W. T., seven miles above the mouth 

 of the Old Man Eiver, E. G. McConnell, 1881 : one nearly perfect 

 specimen with the test preserved on both valves and entirely free 

 from the matrix. 



(3.) From the St. Mary Eiver Series and lower portion 

 OF the Laramie generally. 



In the southern portion of the district included in the geologically- 

 colpured map of the region in the vicinity of the Bow and Belly Eivoi-s, 

 the Laramie, on lithological grounds, is clearly separalsle into three 

 subdivisions, as described in Dr. CI. M. Dawson's report already referred 



