472 THE CANADIAN NATURALIST. [Vol. vi. 



this the sides are gently convex, the dorsum more narrowly 

 rounded. The shell is thin, nearly smooth with very fine obscure 

 striae, about ten in one line. The strise curve forwards on the 

 ventral side, forming an arc the height of which is equal to about 

 one- third the width of the shell. On crossing the lateral edges 

 the striae curve backwards, until they reach the most projecting 

 part of the sides, then cross up and over the dorsum at a right 

 angle. On a side view the shell is gently curved upwards on 

 approaching the apex. 



A specimen 24 lines in length on the ventral side is 8^ lines 

 wide and 6 lines in depth at 20 lines from the apex. 



Occurs in the red limestone at Smith's Sound, Trinity Bay. 



9 • 10 



Fig. 9. Agraulos socialis. The head without the moveable cheeks. 

 The glabella is too distinctly defined in this figure. 



Fig. 10. " strenuus. 



Agraulos socialis, spec. nov. Fig. 9. 



Head (without the moveable cheeks) semi-elliptical or conical, 

 width at the base a little greater than the length, gently convex. 

 Glabella conical and (including the triangular projection back- 

 wards from the neck-segment) about two-thirds the whole length 

 of the head, neck-furrows all across but obscurely impressed ; 

 neck-segment with a triangular projection backwards, terminating 

 in a short, sharp spine. Fixed cheeks gently convex ; front mar- 

 gin sometimes with a portion in front of the glabella thickened. 

 Eyes of moderate size and situated on a line drawn across the 

 head at about the mid-length, distant from each other about the 

 length of the head. Surface nearly smooth. 



In small perfect specimens no trace of glabellar furrows can be 

 seen, but in some of the large ones four or five obscure furrows 

 are exhibited. 



The largest specimen seen is six lines in length and seven in 

 width. It occurs at Chapel iVrm, Trinity Bay. 



