Stewart.] Cretaceous Fishes. 367 



recent Siluridse. The opposite surface is irregularly marked, 

 and one of the extremities is convex. 



Length of alveolar border of dentary 174.5 mm. 



1 toptfa of symphysis 17.0 " 



Number of teeth in one inch, 5. 



Pachyrkizodus latimentum ?.. Plate LXVIII; plate LXX, figs. 9, 10. 

 Pachyrkizodus latimentum f Cope, Proc. Am. Phil. Soc. 1872, p. 310. 



This species of Pachyrkizodus is .the largest American member 

 of the genus, and probably outrivaled some of the largest forms 

 of Ichthyodectes. The specimen was found by myself in the 

 Butte creek region, in Logan county, Kansas, during the summer 

 of 1S9S, and consists of a portion of a disarticulated skull, the 

 glenoid portion of a scapula, and a number of vertebra 4 . The 

 catalogue number of the specimen is 316. 



Both the extremities are broken away from the maxilla, so 

 that the exact length of this bone cannot be determined. It is 

 finely striated externally and internally, and is somewhat 

 coarsely striated on the superior surface. The teeth are large 

 and closely set, but they are not all functional at once. The 

 bases of these are somewhat striated and hidden from view ex- 

 ternally by the downward extension of the outer alveolar wall. 

 The teeth probably end some distance from the posterior ex- 

 tremity, as there is an edentulous portion back of the last tooth 

 that continues as far as the alveolar border is preserved in this 

 direction. The greatest depth of the fragment is 35 mm. 



The premaxilla is more slender and pointed anteriorly than 

 in P. caninus. There are seventeen teeth and tooth scars on the 

 outer border, and there are spaces for one or two more that 

 show no indication of ever having borne teeth. The teeth seem 

 to be very similar to those found on the maxilla, with the ex- 

 ception that they are slightly smaller. The external border is 

 nearly straight, while the internal is beveled off toward the 

 anterior end, giving the extremity a slightly blunted appear- 

 ance. Internal to the regular series there is a tooth that is 

 much larger than those in the external row which lias a deep 



