186 University of Kansas Geological Survey. 



Characteristic differences, other than those of size, absolutely 

 and relatively, are hard to find. Nevertheless I believe that 

 the species will be recognized. 



Platecarpus coryphaeus. 



? Liodon muclgei Cope, Proc. Amer. Phil. Soc, 1870, p. 581. 



Holcodus coryphceus Cope, Proc. Amer. Phil. Soc, Dec. 1871. 



? Lestosaurus gracilis Marsh, Amer. Journ. Sci., June, 1872. 



? Lestosaurus simus Marsh, Amer. Journ. Sci., June, 1872. 



Platecarpus eoryphazus Cope, Cret. Vert., 142, 267, pi. xiv, f. 3; xv, f. 1; 

 xvi, f. 1; xvn, f. 6; xx, f. 4; xxi, ff. 1, 2; xxxvi, f. 6: xxxvn, f. 9; Baur, 

 Journ. Morph., vn, 1; Merriam, Ueber die Pvth. der Kans.-Kreide, 30; 

 Williston, Kans. Univ. Quart., vi, pi. x. 



This species is the best known of the Kansas Mosasaurs, and 

 the most common. Possibly this is due to the fact that it was 

 the best described. "The specimens upon which this species 

 rests were discovered by Prof. B. F. Mudge, formerly State 

 Geologist of Kansas, now professor of geology in the State 

 Agricultural College of Kansas, on the north bank of the Smoky 

 Hill river, thirty miles east of Fort Wallace, Kan." 



The description of the species will be found in detail in the 

 comparative anatomical description, and numerous figures and 

 the restoration will be found in the plates. 



I believe that I recognize at least three synonyms, P. mudgei 

 Cope, P. gracilis and P. simus Marsh. From the inadequacy of 

 the descriptions of these species I may be in error. Nothing 

 but an examination of the type specimens Avill determine the 

 matter. Should P. mudgei be found identical, the name must 

 supersede corypha us. 



I give, however, the descriptions of all three of these species 

 quoted from their authors. 



Platecarpus mudgei. 



Liodon mudgei Cope, Proc. Amer. Phil. Soc, 1870, 581. 

 Holcodus mudgei Cope, 1. c, 1871, December. 

 Rhinosaurus mudgei Marsh, Amer. Journ. Sci., June, 1872. 

 Platecarpus mudgei Cope, Cret. Vert., 157, 268, pi. xvi, f. 3; xvn, f. 5; 

 xxvi, f. 3; xxxvii. f. 7. 



"The characters distinguishing this saurian are the follow- 

 ing : Vertebrae without rudimental zygosphene ; quadrate bones 



