Note J — Chapter III
Reading edition
Agassiz now reckons ten distinct species of Pterichthys—P. arenatus, P. cancriformis, P. cornutus, P. major, P. Milleri, P. latus, P. oblongus, P. productus, P. testudinarius, and P. hydrophilus; of these, nine species belong to the Lower, and one—the Pterichthys hydrophilus—to the Upper Old Red Sandstone.