Fig. 25 



Fig. 27 



Fig. 25. A, Trinacromerum osborni Williston. Plesiosaur: left mandible to sym- 

 physis, inner side, after Williston, 1903; B, Captorhinus agtiti Cope. Cotylosaur: 

 left mandible, from within; C, the same, outer side. 



Fig. 26. Limnoscelis paludis. Cotylosaur. Outline of back of skull. Two fifths 

 natural size. 



Fig. 27. Cotylosaur. Inner side of mandibles. A, Limnoscelis paludis; B, Labi- 

 dosaurus hamatus. One half natural size. «r/, articular; 9, quadrate; J«r,surangular; 

 cor, coracoid; pa, prearticular; ang, angular; sp, splenial. 



39 



