Stewart.] Cretaceous Fishes. 293 



Xiphactinus lowii. Plate XLVIII, fig. '2. 



Portheua lowii Stewart., Kans. Univ. Quart., vol. vii-a, p. 24. 



This species is based on the dentary bones of a single indi- 

 vidual found at Fairbury, Neb., in the same horizon of the Fort 

 Benton Cretaceous with Desmatochelys lowii, and was sent to the 

 museum by Mr. M\ A. Low, of Topeka, in whose honor the 

 species is named. While this specimen has not been reported 

 from Kansas up to the present time, yet it no doubt occurs 

 here, as the same horizon from which it was obtained is found 

 just across the line in this state. Special interest is attached 

 to this specimen, as it is the first of this genus to be reported 

 from so low a horizon as the Fort Benton. 



The dentary is short, with a more oblique symphysis than in 

 any other specimen of Xiphactinus that I have examined. It is 

 also not so roughly marked at this point for the attachment of 

 ligaments as in A', audax. The alveolar border is short, and 

 does not have the prominent swelling just back of the symphy- 

 sis which is found in the species just mentioned. The posterior 

 extremity is projected upward into a short coronoid process, 

 which is bent outward but slightly. The teeth are slightly 

 oval in cross-section, acutely pointed, directed slightly back- 

 ward at the extremities, and non-striate even under the micro- 

 scope. Their arrangement is as follows : One large, two small, 

 one large, ten or eleven medium and small. The number and 

 arrangement will no doubt vary with the individual. 



Length of alveolar border 177.0 mm. 



Length of symphysis 79.5 " 



Depth of hone just back of symphysis 65.0 " 



Depth of dentary at middle (54.5 " 



Xiphactinus hrachygnathus. Plate XLV, figs. 3, 4. 



Xiphactinus hrachygnathus Stewart, Kans. Univ. Quart., vol. viii. 



In addition to the forms described above, there is one speci- 

 men that I am unable to locate as A'. Ustrio or A', mudgei, 

 described by Professor ('ope. As lias been shown above, Cope 

 based most of the specific differences on very inconstant char- 

 acters in his description of .V. molo88tb8 and A', than mas, and as 

 he has used much the same characters in his description of the 



