30 THE ORIGIN OF VERTEBRATES 
Fic. 11.—Pteraspis dunensis (from Drevermann). Dorsal view of body and spine 
on the right side. Head-end, showing long rostrum on the left side. 
Fic, 12.—Bunodes lunula. (From Fic. 13.—Auchenaspis (Thyestes) verru- 
ScuMIpT.) cosus, natural size. (From WoopwaRD.) 
