376 New Species of Trilobites. 



and elevated behind. , The front margin is nearly straight or only 

 gently convex in the middle third, then straight, but turned back- 

 wards to the ends of the pleura?, where it meets the posterior 

 margin nearly at a right angle. 



Surface smooth. 



Allied to /. Trentonensis, but in that species the dorsal furrows 

 are continued on the head and in the cast of the interior extend 

 nearly to the front margin, where they terminate in two small 

 circular pits. 



Dimensions of a small nearly perfect specimen, not the one 

 figured : — 



Total length 14| lines. 



Length of head ^ " 



Width of head 13£ " 



Distance between eyes .'.... 11 " 



Length of thorax 4£ " 



Distance between the lines of the bend of 



the pleurae . - 8£ " 



Length of pygidium 5£ " 



Width 8£ " 



Dedicated to the late Hugh Miller, the eminent Scotch 

 geologist. 



Locality and formation. — This species occurs in the Trenton 

 limestone at St. Joseph's Island, Lake Huron ; at the city of 

 Ottawa; at L'Orignal, and at various other localities in the 

 valley of the Ottawa. Also in the Black River limestone, at the 

 Falls of La Petite Chaudiere, township of Hull. 



Ill^nus Trentonensis. (Emmons.) 



This species occurs at La Petite Chaudiere, township of Hull, 

 and at the Mingan Islands in the Black River limestone 



Ill^enus ovatus. (Conrad.) 



This species occurs at La Petite Chaudiere, township of Hull, 

 in the Black River limestone. 



Of the following species, imperfect specimens have been found ', 

 but they are evidently distinct f mm any of the preceding . 



Ill^enus angusticollis. (N.s.) 



Description. — Of this species only the head has been found, 

 and the most remarkable peculiarity it presents is the very nar- 



