HOW THE FISHES LEARNED TO SWIM — HEINTZ 235 



SubOrd-Pheras^spida & SubOrcl Psaimmosteida. 



Figure 7. — Different representatives uf tlie suborders Fteraspida and I'sammosteida (after 

 Kiaer, Bryant, Gross, Lerich, and Traqiiair). A, a small Ptcra-^pis from SpitzlH-rsen ; 

 from above, below, and from the side. B, Protaspix. a form from America ; seen from 

 above. C, Pteraspis from Germany. D, Pteraspis from France. E, Dyrcaspis, a new 

 form from Spitzbergen. F, Drcpanaspis from Germany. 



