THE CUTANEOUS SENSE ORGANS. 



357 



tral side, except for a short line, or dash, on one or two of the oral plates. (Fig. 

 237. 4.) 



In Bothriolepis the lines form continuous shallow grooves. (Figs. 247, 248.) 

 One line extends from the infra-orbital across the front of the head; there is a 

 V-shaped orbital line connected with the occipital pores, and one on the dorsal sur- 

 face of the branchial shield; another extends onto the ventral surface, across the 

 maxillary plates, probably connecting with the line on the premaxillary plates; 

 while a lateral line extends along the sides of the branchial shield and appears to be 

 continuous with a furrow extending along the sides of the fleshy trunk. 



FIG. 234. A small species of Cephalaspis, sp.' associated with Bothriolepis, from Miguasha, Bay Chaleur, P. Q. 

 About natural size. A, From side; B, haemal surface; C, cross-section of the trunk; D, sagittai section of the head 

 E, cross-section of the head. In B, a heavy bony ridge is seen, b, that probably divides the oral from the bron- 

 chial chamber. From specimens in the author's collection. 



In Pteraspis and Palaeaspis there are scattered dash-like markings on the 

 outer surface similar to those of Tremataspis, but less regularly arranged. There 

 is also a special system of canals lying within the shell, the distribution of which 

 is imperfectly known; they may perhaps represent closed lateral line canals 

 (Tremataspis, Pteraspis, and Palaeaspis) 



In Ateleaspis, nov.sp, from Dalhousie, sensory grooves are present similar to 

 those in Tremataspis, but located on a narrow ridge. The infra-orbital, the ant- 

 orbital, and the anterior end of the lateral line, are indicated. (Fig. 242.) 



