64 Silurian Fossils of Canada. 



across tbe glabella. The sides of the glabella are curved a little 

 inward at the posterior lobes and then outwards to the outer 

 extremities of the anterior furrows. The neck segment is large 

 and has its posterior margin rather stronnjly elevated. The cheeks 

 are moderately tumid. The eyes are semicircular, prominent, 

 one fourth the whole length of the head, about their own length 

 from the posterior and a little more than their length from the 

 anterior margin ; the distance between their centres appears to 

 be aoout one twelfth or one fifteenth greater than the length of the 

 head. The surface of the glabella is ornamented with small rounded 

 tubercles of various sizes, the largest being about one fifth of a 

 line in diameter at the base and, in general, distant once or twice 

 their own width from each other. Surface of cheeks not yet 

 distinctly observed but appears to be smooth. In none of the 

 specimens are the lenses of the eyes preserved. 



Thorax with eleven segments; axis well defined and appa- 

 rently as wide as the side lobes, but this character cannot be suffi- 

 ciently determined, as all the specimens are crushed. Length of 

 the thorax once and a half the length of the head. 



The pygidium in the only specimen that I have seen in which 

 any considerable portion of it remains attached to the body, has 

 the posterior extremity broken away. Judging however from 

 the curves of the posterior margin I think it probable that there 

 is no terminal spine as there is in most of the species of this 

 genus. There are about ten segments in the axis and apparently 

 ten in the side lobes. If the pygidium have no terminal spine 

 the proportional lengths of the specimen figured would be very 

 nearly as follows : 



Head, ...... 5 lines. 



Thorax, .... TJ lines. 



Pygidium,. . . 5 lines. 



Total 17 J lines. 



On comparison it w'll be seen that this species diff'ers from D 

 Behryx in the form of the glabella and in the number of seg- 

 ments in the central lobe of the pygidium. 



Locality and Formation. — City of Ottawa, Trenton limestone, 

 very rare. Collector, — E. Billings. 



