236 



Mr. R. Broom on the 



But though in front it has a smooth edge the posterior edge 

 is irregular, as if indicating an ossification in cartilage. The 

 anterior ossification or ossifications probably correspond to 

 the sphenethmoid of Siredon or the frog, and the posterior 

 to the ossification seen in Dinosaurs, Crocodiles, and birds, 

 and usually, but I think wrongly, called alispbenoid. 



The quadrate is large aud its upper half is largely hidden 

 by the squamosal. There need not, I think, be the slightest 



Fig. 2. 



& Ang. 



P. Art. 



Lower jaw of Lysorophus triearinatus, Cope, X 5. A represents a 

 section at a a. 



Any., angular; D, dentary; P. Art., prearticular ; S.Any., surangular. 



Fig. 3. 



ff Pa.Sp. ^ > 



Pt. 



Pty> 



P. Art 



y 



S.Anc 



'An,. 



Section across skull and jaw of Lysorophus triearinatus, Cope, X 5. The 

 section of the lower jaw is near the point indicated by b b in the 

 figure of the jaw. The outer corners of the parasphenoid are sepa- 

 rated by cracks or sutures. They are believed to be parts of the 

 parasphenoid. 



Any., angular ; Pa., parietal ; Pa.Sp., parasphenoid ; P.Art., prearticular ; 

 Pt., pterygoid ; S.Any., surangular. 



doubt about this bone being the squamosal — the view also 

 held by Williston and v. Huene. 



The occiput has recently been figured by v. Huene from 

 one of the American Museum specimens and also from one 

 of the Tubingen specimens. His drawing of the American 

 Museum specimen is not in my opinion quite accurate, the 

 American specimen agreeing closely with his figure of the 

 Tubingen specimen. The main difference between the two 



