282 NORTH AMERICAN INDEX FOSSILS. 



66. C. pecten (Salter). (Fig. 1581, c, rf.) Cambric. 

 Glabella parallel-sided and reaching the frontal margin. Divi- 

 sions of the axis of the pygidium prominent only on its sides. 



Upper Cambric (Bretonian) of Cape Breton, New Brunswick. 



67. C. acadica Matthew. (Fig. 1582, a-^.) Cambric. 

 Spine of free cheek opposite median portion of head and strongly 



curved. The rectangular hypostoma, wholly bordered by a margi- 

 nal fold, consists of an oval anterior portion and a lower crescent- 

 shaped posterior portion. 



Upper Cambric (Bretonian) of New Brunswick. 



XXX. Sph^ropthalmus Angelin. 



Similar to Leptoplastus, but middle lobe of body broad, posterior 

 portion of fixed cheeks narrower, genal spine long and arched, eyes 

 spherical and noticeably facetted. Thorax with seven to nine seg- 

 ments. Pygidium triangular, without spines. Cambric. 



68. S. fletcheri Matthew. (Fig. 1581,^-5^.) Cambric. 

 Genal spine sickle-shaped, long, flat, very wide and stiffened by 



two sharp ridges that run along the middle. Pygidium with a 

 tubercle at each anterior outer corner, and each axial segment with 

 an obscure lobe at each side. 



Upper Cambric (Bretonian) of Cape Breton. 



69. S. alatus (Boeck) var. canadensis Matthew. (Figs. 1582, a', h' ; 

 1583.) Cambric. 



a 



b 



FiG. 1583. Sph(Bropthalmus alatus V2X. canadensis, y^\. (After Matthew. ) 



Free cheeks semilunar in outline; genal spines round and com- 

 paratively short in the broad form, but long and flattened and with 

 a ridge along the middle, in the narrow form of this variety. 



Upper Cambric (Bretonian) of New Brunswick and Cape 

 Breton (?). 



