Fossils of the Calciferous Sandroch 365 



^ BATHYURUS AMPLIMARGINATUS, (N. S.) 

 Fig. 12, a, b. 



Description. — The pygidium of this species is nearly semi-cir- 

 cular its length being only a little more than half its width ; the 

 axis is elongate conical very prominent and distinctly defined all 

 round, its length about two thirds, and its greatest width one fifth 

 that of the whole pygidium ; it is crossed by five distinct transverse 

 furrows but the terminal one third is either smooth or marked by 

 extremely obscure sulci. On each side of the axis there are 

 five ribs ; the first of these is only partly preserved in the speci- 

 men, the second at about half its length contracts to one half its 

 width and appears to become obsolete before reaching the margin ; 

 the third rib is in length equal to the width of the axis at the point 

 where it is attached ; the fourth a little shorter, while the fifth is 

 simply a triangular convex space between the fourth furrow and 

 the posterior third of the axis. The most striking character is 

 the broad smooth margin, the width of which is about one fourth 

 that of the whole pygidium. 



Fig. 12. 



a — b Bathyurus amplimarginatus. 

 c Bathyurus conicus. 

 d Bathyurus Cybele. 



Associated with this pygidium and in the same mass of stone 

 was found the glabella represented by Fig. 12, a. It is depressed 

 cvlindro-conical, length eight lines, width four lines and a half, a 

 strong neck segment one line and a half in width. 



Locality and formation. — Mingan Islands, White limestone. 



Collectors. — Sir W. E. Logan. J. Richardson. 



