32 WATSON & Day, Notes on sonic Palceozoic Fishes. 



below by another ridge. Although we have no direct 

 evidence that such is the case, we believe that these ridges 

 mark the position of the posterior vertical and horizontal 

 semi-circular canals which in this case must be of great 

 size, just as they are in the living Ceratodus. In advance 

 of the otic region, the less well-ossified chondrocranium 



Text-fig. 6. — Dipterns platyctphalus, Pander. Restoration of 

 the palatal aspect of the head with the circumorbital and opercular 

 bones removed. Natural size. 



joins the quadrate with which indeed it seems to be 

 continuous. The general structure of the parasphenoid, 

 pterygoids and quadrates has long been known, but we 

 would note that the quadrate sends forwards a ptery- 

 goidal process in front of the quadrate ramus of the 

 pterygoid, just as it always does in Stegocephalia. 



