424 OLIVER p. HAY 



Doctor Versluys affirms, without admitting that his conclusion 

 follows. A secondary palate is a possession of some turtles of 

 all the higher divisions of the order, and there is hardly a possi- 

 bility that these secondary structures have been derived in all 

 cases from a common source. The early representatives of the 

 Athecae were probably swamp- or coast-frequenting species 

 and they may have subsisted on hard food; the mastication of 

 this may well have developed a secondary palate. Having later 

 taken more and more to Ufe in the sea and to soft food, the palate 

 may have gradually degenerated to its present state. 



We are indebted to Doctor Versluys for the finding of a large 

 parasphenoid bone in Dermochelys (Zool. Jahrb. Anat., Bd. 

 28, S. 283-294) and his discovery appears to be confirmed by two 

 disarticulated skulls in the U. S. National Museum. Inasmuch 

 as this bone has not been recognized in any of the other sea tur- 

 tles, Versluys concluded that there was no close relationship 

 between the Cheloniidae and Dermochelys. Certainly, if the 

 latter genus had been derived from any of the Cheloniidae, we 

 might expect that some of the Cretaceous members would possess 

 a parasphenoid. 



On the part of those who beheve that Dermochelys and its 

 alhes have been derived from the chelonioid Cryptodira, much 

 importance has been given to the fact that the eighth cervical 

 in both the Cheloniidae and Dermochelys forms an articulation 

 with the nuchal, and Doctor Versluys makes allusion to it. 

 To the writer it appears that this articulation has lost its impor- 

 tance as a mark of kinship. From Versluys (p. 322, footnote) 

 we learn that Menger has discovered that the nuchal is a com- 

 posite bone, one layer of which may have been derived from 

 the ribs of the hindermost cervical. This could hardly have 

 come to pass without a close connection of the neural arch of 

 that vertebra with the nuchal. Jaekel (Palaeont. Zeitschr., 

 Bd. 2, S. 102) has found that in his Stegochelys (Triassochelys) 

 the spinous process of the eighth cervical (Jaekel's first dorsal), 

 as well as that of the succeeding vertebra, is attached without 

 suture to the nuchal. In the great majority of these reptiles 

 the connection has been dissolved; in the sea-inhabiting mem- 

 bers of the group it has, for special reasons, been retained. 



