;o 



THE ORIGIN OF VERTEBRATES 



Fig. 11. — Ptcraspis duncnsis (from Drevermann). Dorsal view of body and spine 

 on the right side. Head-end, showing long rostrum on the left side. 



Fig. 12. — Bunodes lunula. (From 

 Schmidt.) 



Fig. 13. — Auclicnaspis (Tkyestes) verru- 

 cosus, natural size. (From Woodward.) 



