THE CUTANEOUS SENSE ORGANS. 



357 

 (Fig. 



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



237^0 



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.f 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, sagittal 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.) 



