^rof. T. Rupert Jones — Canadian Osfracoda. 21 



the Milk Eiver, in Southern Alberta, North-west Territory, but 

 belonging to the Saint-Mary-Eiver Beds. Collected by Dr. G. M. 

 Dawson in 1874, when he was the Geologist and Botanist to the 

 British North-American Boundary Commission. 



III. Some specimens from the Saint-Mary-Eiver Beds of the 

 Lower Laramie series, on the North Branch of the Milk Eiver, and 

 of either newest Cretaceous, or oldest Tertiary age ; also collected 

 by Dr. G. M. Dawson in 1874. 



IV. One small specimen from the St.-Mary-Eiver Beds ; collected 

 by Dr. G. M. Dawson in 1881, on the Old-Man Eiver in the 

 Alberta District. 



With regard to II. and III. we note that in Dr. Dawson's "Eeport 

 on the Geology and Eesources of the Eegion in the Vicinity of the 

 Forty-ninth Parallel," etc., 1875, the geology of the First [now 

 the South] Branch of the Milk Eiver is briefly noticed at page 130 ; 

 and the Second [now the North] Branch (14 miles to the west) at 

 page 131. The fossils generally at these sections appear to have 

 freshwater characters for the most part (pages 155-158). See also 

 further on, page 25. 



§ 2. Description of the Species. 



From among the several more or less distinct examples, the 

 following have been selected. 



Only with two or three of the figured specimens (as Figs. 1 and 3) 

 is there direct evidence of the exact outline of the margins of the 

 valves, as shown in Figs, b and c throughout the series, owing to 

 the imbedment, or the close adherence of the valves to the rock by 

 their edges. For the same reason, for want of direct evidence of 

 the hingement of the valves, the generic position of the majority is 

 very uncertain, and only provisionally suggested. 



Mr. Frederick Chapman has kindly helped me in preparing and 

 determining the specimens. 



I. Seven small pieces of grey and yellowish friable marl, con- 

 taining numerous thin shining valves, and casts of similar forms. 

 These are from the Eolling Eiver, Manitoba. The geological 

 conditions are described at pages 115 E, and 116 E, of the "Eeport 

 on North-western Manitoba, with portions of the adjacent districts 

 of Assiniboia and Saskatchewan." By J. B. Tyrrell, M.A., B.Sc, 

 F.G.S. Part E of Annual Eeport of the Geological Survey of 

 Canada, vol. v. 1889-90-91. 8vo. Ottawa, 1892. 



Thus :— 



Eolling Eiver was examined from a point a short distance west 

 of the 101st meridian, where it is about 2250 feet above the sea. It 

 is here a small stream in a valley fifteen feet deep, with a Spruce 

 swamp on both sides. Its bed is covered with boulders, and its 

 channel is much obstructed by beaver-dams. A short distance lower 

 down it flows in a deep valley, the sides of which show some 

 excellent sections of Pleistocene deposits. One of these sections 

 on the north bank is as follows : — 



