294 Canadian Record of Science. 



lower of these two subdivisions, and the Strophomena and 

 Acidaspis from the upper. 



Brachiopoda. 



Strophomena acanthoptera. (Sp. nov.) 



Plate iii, figs. 1 and 2. 



Shell varying in outline from broadly semicircular or 

 semioval and regularly rounded in front, to subtrigonal 

 with the front margin produced and somewhat pointed in 

 the centre, — but always broadest at the cardinal margin, 

 which is produced on each side into a long, very slender, 

 and slightly curved spine ; length of each cardinal spine a 

 little more than one half of the greatest breadth of either 

 valve without the spines. Ventral valve regularly convex 

 from beak to front, though the nasute forms are most pro- 

 minent anteriorly along the median line ; umbonal region 

 compressed ; beak small and raised very little above the 

 general level of the hinge line ; ai'ea transversely elongated 

 and very narrow in the direction of its height, with a small 

 equilateral foramen in the centre. Dorsal valve concave, 

 with a perfectly straight cardinal margin, an extremely 

 minute beak and a hinge area much narrower than that of 

 the ventral. 



Surface marked by numerous, but comparatively distant 

 and, for the most part simple, radiating raised lines, which 

 increase by intercalation and alternate at unequal distan- 

 ces with from one to five (or perhaps more) shorter and 

 much smaller ones, the whole being crossed by extremely 

 minute and close set concentric striations, and by a few 

 more or less distant lines of growth. Characters of the in- 

 terior unknown. 



Collected at several localities on the northern portion of 

 the east shore of Lake Winnipegosis, in the district of Saskat- 

 chewan and in the adjacent part of the Province of Mani- 

 toba by Mr. J. B. Tyrrell in 1889, (but previously found 



