THE ELASMOBRANCH FISHES 263 



their arrangement. ]\Iost of these pits lie between the segment of the spiracle 

 and the dorsal fin althongh four of them lie near the middorsal line in front 

 of the apertures for the endolymphatic ducts. Further, a line extends down 

 the arch back of the spiracle, as the so-called gular line (gl., fig. 228) described 

 by Garman (1888) for Chlamydoselachus. This passes downward and for- 

 ward in front of the first branchial cleft and ends ventrally before reaching 

 the mandibular symphysis (fig. 227b). 



