Chapter 31 THE HOLOCEPHALI, OR CHIM RAS

The Chim?ras.-Very early in geological times, certainly as early as the middle Silurian, the type of Chim?ras diverged from that of the sharks. Hasse derives them directly from his hypothetical primitive Polyospondyli, by way of the Acanthodei and Ichthyotomi. In any event the point of divergence must be placed very early in the evolution of sharks