PLATE LV. 



PAGE. 



AcANTJiASPis ARMATUS, Newb 37 



Fig. 1. Plate bearing spine, from left side of cranium ? 



2. Plate bearing Kjiine, from riglit side of cranium ? 



3. Plate corr('si)im(liiig to fig. 2, from another individual, showing the manner in which the 



spine was jdiiiod to the exterior border. 



4. Under side of a plate generally similar to fig. 3, but holding a different position, or belong- 



ing to a different species. 



5. Exterior surface of a plate found associated with other remains of Acanthaspis. 

 5a. Ornamented surface. Twice natural size. 



6. Inside of plate similar to fig. 3, but detached from its spine. 

 All figures, except 5a, natural size. 



All originals from the Corniferons limestone, Sandusky, Ohio. 



