On the Anatomy and Phylogebetic Position of Polypterus. 



413 



R. pipiens is a separate bone occupying a position similar to that in 

 Polypterus. In the Reptiles there are 4 pairs of bones, pterygoids, 

 transverse, palatines and vomers and it seems quite possible that the 

 so called pterygoids may be metapterygoids , the transverse may re- 

 present the ectopterygoid and the palatines the entopterygoid. How- 

 ever I only venture to put this forward as a suggestion. In seeking 

 for a form to derive the condition of the teeth in Polypterus it will 

 be seen that Chlamydoselachus is a satisfactory as any though one 

 has to neglect the specialized form of the palatopterygoid teeth. 



The mouth and throat are lined with shagreen. To evolve the 

 condition of Polypterus one has to consider the bases of teeth lying 

 below the cranium and anterior two vertebrae as fusing to form the 

 parasphenoid, while in front similarly some teeth form the subrostral 

 bone. Below the quadrato - pterygopalatine bar certain teeth bases 

 early form the metapterygoid, ectopterygoid and vomer, the metaptery- 

 goid arising below the quadrate, the ectopterygoid below the pterygoid 

 cartilage behind the ethmopalatine articulation and the vomer below 

 the iuterarticular region. In Selachii the corresponding teeth are 

 always present but do not fuse by their bases. The entopterygoid 

 arises in the roof of the mouth between the palatopterygoid bar and 

 the floor of the cranium. 



Woodcut 6. 



Woodcut 7. 



Woodcut 6. Palatal region of Rana pipiens from Parker. 



Woodcut 7. Palatal region of Polypterus. 



1 Vomer, 2 Palatine or entopterygoid, 3 Pterygoid or ectopterygoid, 4 Metapterygoid, 

 Space below the eye which becomes so great in Anura. 

 Zool. Jahrb. V. Abth. f. Morph. 28 



