Stewart.] Cretaceous Fishes. 327 



The top of the skull is very Hat in both genera, and made up 

 for the most part of the elongate, triangular-shaped frontals, 

 which are united in the median line by means of a long, 

 straight suture. These bones are covered on the superior sur- 

 face by small ridges or striae, which radiate from a point inter- 

 nal to the postorbitals and are most strongly marked in Empo. 

 The supraoccipitals are small and invade the top of the skull 

 but little. It is raised into a slight crest in Empo, and prob- 

 ably so in Stratodus. 



Below is given a revised synopsis of the family : 



I. Premaxilla short, with several rows of teeth : 



Palatine and mandibular teeth numerous, in several 



rows Stratodus. 



II. Premaxilla elongate, with one row of small teeth: 



Mandibular teeth in two series, of which the outer are 

 small and in several rows, while the inner are very 

 large. 



Palatine teeth large and in two rows Empo. 



III. Premaxilla and maxilla elongate, with very small teeth: 

 Palatines and ectopterygoids provided with powerful 



teeth, some of which are semibarbed in shape Cimolichthys. 



STRATODUS. 



This genus, as characterized by Cope, is remarkable for the 

 small size, great number and peculiar form of the teeth. Un- 

 fortunately the material from which the descriptions have been 

 made was very fragmentary, from which no adequate conception 

 of the cranial characters could be obtained. The jaws as well 

 as most of % the bones are very fragile, and it is probably owing 

 to this fact that no perfect specimens have been collected. The 

 geological expedition of 1898 to western Kansas obtained a 

 specimen belonging to this genus from near Twin Buttes, Wal- 

 lace county, that shows some points not known before. The 

 specimen is far from perfect, but it is much better than any 

 specimen heretofore described. 



The premaxilla is small and has three or four rows of teeth 

 on the lower side, of which those on the inner are the largest. 

 The dentaries are \ovy slender and are covered with numerous 

 rows of small conical tpetli on the internal side which are all 



