310 University Geological Survey of Kansas. 



which is even greater than in Xiphactinus. The bones are very 

 thin. 



One specimen has fifty-seven vertebrae preserved, and there 

 are probably several more missing. So far as can be deter- 

 mined, this specimen was at least four feet in length, and, 

 judging from the skull, it does not seem to be larger than the 

 other specimens. 



SAURODONTIDiE. 



The characters that separate this family from the Ichthyodec- 

 tidse are found in the presence of a predentary in the mandible 

 and in the form and manner of succession of the teeth. In 

 other respects the skull is very similar to that of the Ichthyo- 

 dectidve, except that it is likely that Saurodon possesses a tooth- 

 bearing element not found in this family. The predentary is a 

 long, triangular element, pointed at the extremity, and was used 

 as a weapon of offense. Contrary to what would be expected, 

 this bone is not paired, and is also edentulous in both genera 

 of this family, Saurodon 'and Saurocephalus. Doctor Crook 69 has 

 removed one of these genera, Saurocephalus, to the family Pachy- 

 cormidse, the reasons for which are : 



"Das Dentale hat andere Proportionen als dasjenige von Ichthyo- 

 dectes und Portheus [Xiphactinus^\ indem es viel niedriger und gegen 

 die zahntragende Oberflache dicker wird. Die maxilla ist mehr dick 

 als tief , die Prsemaxilla dreieckig und lang, die langste Seite als zahn- 

 tragender Rand ausgebildet. Sie ist so ganzlich verschieden von 

 denjenigen der anderen Glieder dieser Familie, dass dies Merkmal 

 allein genligt, urn Saurocephalus einer anderen Gruppe zuzuweisen. 

 Diese Annahme wird noch mehr bestatigt durch den Charakter der 

 Maxilla und des Dentale, die Foramina und die Art und Weise der 

 Aufeinanderfolge der Zahn. Auf Grand der Gleichartigkeit der 

 Zahnea und der auserordentlichen iEhnlichkeit der Prsemaxilla rait 

 derjenigen von Protosphyrama diirfen wir Saurocephalus bis auf 

 weiters in die Familie von Protosphyrmnidm einreihen." 



Concerning the above, I would say that I have been unable 

 to recognize the great similarity between the premaxillse of the 



69. Paleontographica, 1892, p. 120. 



