PEOM TiiE District OF ATHABASCA. i2i 



EXPLANATION OF PLATES. 



PLATE VIII. 



Dbsmocbras affine. (Page 113.) 



Side view of one of the most perfect specimens of tlie typical form of this species, three-fourtlis ttie natural 

 size. 



PLATE IX. 



Desmockeas affine, Var. glabrum. (Page 115.) 



Side view of the largest known specimen of this variety, also three-fourtlis the uatural size. In this 

 drawing the tine radiating strife are represented somewhat diagrammatically. 



PLATE X. 



Desmooeras Athabascbnse. (Page 116.) 



Fig. 1. — Side view of the type and only known specimen of this species, one-half the natural size. 

 " la.— Front view of the same, to show the characters of the periphery and aperture, in outline only and reduced 

 to one-tenth the natural size 



PLATE XL 



Desmoceras affine. (Page 113.) 



Fig. 1.— Side view of a half grown specimen of this species, to show the periodic arrests of growth. Natural size- 

 " la. — Front view of the same, in outline only, also of the natural size. 



Hoplites McCoNNBLLi. (Page 117.) 



Fig. 2. — Side view of the largest known specimen, of the natural size. 

 " 2a. — Front view of the same, in outline only, also natural size. 

 " 2b. — Suturai line of one side of the same, of the natural size. 



HopuTES Canadensis. (Page 118.) 



Fig. 3. — Side view of the largest specimen collected, of the natural size. 

 " 3a. — Front view of the same, in outline only and of the natural size. 

 " 4. — Suturai line of one side of a smaller specimen of this species, of the natural size. 



" 5.— Single valve of an Aplychns found in the same piece of stone as the original of figs. 3 and 3a, and probably 

 referable to the same species. Natural size. 



Sec IV., 1892. 16. 



