PLACOGANOIDEI 



121 



fish in shuffling along the sandy bottom or bed, if left dry at 

 low-water. The fins attached to the flexible part of the body 



Fig. 43. 

 Pterichthys Milleri, dorsal surface (Devonian), after Pander. 



indicate a certain power of swimming, though not with any 

 great rapidity ; they include a small dorsal and a pair of 



