202 



CEPHALASPIDOMORPHI 



In the Ateleaspidae the scales on the sides of the body are set 

 in transverse rows, which fuse at the sides to transverse plates in 



Fio. 175. 



Ccpkalaspis Lyelli, Ag. ; restoration of dorsal shield. (After Lankester, from A. S. ^yood- 

 ward.) a./, antorbital fossa ; a.p, antorbital prominences ; i.g, interorbital groove ; i.p, inter- 

 orbital plate; m.c, 'marginal cells'; o.r, orbital rim; p.a, posterior angle; p.<; posterior 

 cornu ; p.ov, postorbital depression ; p.r, posterior ridge ; p.s, posterior spine ; r, rim. 



-pa. 



ds. 



Fio. 176. 



Tremataspis Schmidtl, Rohon, enlarged. A, ventral, and B, dorsal view of the shields. 

 (After Patten.) a.a, anterior area with polygonal plates ; a.m.o, anterior median opening ; d.s, 

 dorsal shield ; LI, pits of lateral line ; m, mouth ; m.a, median area with plates ; or, orbit ; p.a, 

 posterior area with plates ; pl.o, lateral opening ; v.o, ventral openings, probably branchial ; 

 v.p, ventral plates ; v.s, ventral shield. 



