326 University Geological Survey of Kansas, 



STRATODONTID^l. 



The family Stratodontida ', as accepted by Professor Cope in his 

 11 Cretaceous Vertebrata," embraced certain genera of physosto- 

 mous fishes which bear a general relationship to Esox, and in- 

 cluded the genera Stratodus, Empo, Pachyrhizodus , Enchoclus, 

 Tetheodus, and Anogmius, for which the following synopsis was 

 given : 



I. Premaxillary with several rows of teeth : 



Palatine teeth numerous, large; all with pulp cavity, Stratodus. 

 II. Premaxillary with two rows of teeth: 



Maxillary bone short; dentary with equal large inner 



teeth and outer rows en brosse Empo. 



Maxillary bone very long; one row of equal dentaries, Pachyrhizodus. 

 III. Premaxillary with one or no row of teeth: 



A large premaxillary faDg; anterior maxillary and 

 dentary teeth enlarged; cutting edges not oppo- 

 site ; unsymmetrical Enchodus. 



Premaxillary toothless; anterior maxillary and den- 

 tary enlarged Tetheodus. 



The characters of these genera are so varied that I have 

 thought it best, in the present work, to divide the old family of 

 the Stratodontidfe into four separate families, and to use this 

 name for Stratodus, Empo, and Cimolichthys, which may seem 

 remarkable when the great difference in the form of the teeth 

 and tooth-bearing elements of the genera are taken into con- 

 sideration. In Stratodus the teeth are all small and present 

 a great similarity throughout the whole dental series, while in 

 Empo they are of a different size and form on the several parts, 

 and all are different from those in Stratodus. There are also 

 marked differences in other parts, as the form of the palatine 

 and the different lengths of the prem axillae. 



Notwithstanding all these differences, when we examine the 

 top of the skull of each, a remarkable similarity between the 

 two is seen, from which resemblance of the two forms we must 

 conclude that there is a close relationship between the two, 

 notwithstanding the differences of habits indicated by the 

 dentition. 



