38 A REVISION OF THE COTYLOSAURIA OF NORTH AMERICA 



specimen is entitled to consideration as a separate genus from Pariotichus. I can 

 see, however, no warrant for the reference of the specimens from Linton, Ohio, to 

 this genus. The figure published by Cope (20) showing the skull and lower jaw of 

 the Linton specimen does not permit such a reference; the orbits are smaller, pro- 

 portionately, and the lower jaw has not the prominent coronoid process. Only the 

 anterior part of the body is shown and there is no warrant for connecting it with 

 the specimen figured by Cope (43), Williston (66), and Moody (51) as Isodectes copei 

 (puntculatus), in which only the posterior part of the body is preserved. Nor is 

 there any certainty that either of them can be connected with the type skull. 



Family CAPTORHINIDAE nov. 



1. Small, but larger than the Pariotichidce. Skull acuminate, rugose. 



2. Basioccipital and basisphenoid small; not forming a plate on base of skull. 



3. Incisor teeth much enlarged, tusk-like. Cheek teeth gradually increasing 



in size to the middle of the series and then decreasing, to the posterior end. 

 More than one row in the jaws. 

 Other characters as given in the suborder. 



Genus CAPTORHINUS Cope. (Plate 11, figs. 1, 2, 3.) 



Captorhinus, Proe. Am. Phil. Soc., vol. xxxiv, 1896, p. 443. 

 Pariotichus, Proc. Am. Phil. Soc., vol. xxxiv, 1896, p. 443. 



Captorhinus angusticeps Cope. 

 Proc. Am. Phil. Soc., vol. xxxiv, 1896, p. 443. 



Type: An imperfect skull with both rami of the jaws in place. No. 4438 Am. 

 Mus. Nat. Hist. Cope Coll. From Texas. 



Original description. Genus and species: "The head is wedge-shaped, with an 

 acuminate and rather elongate muzzle. The orbits are round and rather large, the 

 diameter being double the interorbital width, and equal to the length of the muzzle 

 to the middle of the nostril. The teeth increase in length gradually from behind 

 forwards, and the anterior mandibular teeth are inclined forwards at an angle of 

 45°. The premaxillary teeth have lost their crowns, but from the direction of the 

 alveolae, it appears that they were not directed posteriorly to any conspicuous degree. 

 The posterior teeth of both jaws have obtuse crowns, and the crowns become more 

 and more conic to the front. Nothing can be said of the character of the sculpture, 

 as the surface of the bone, where present, is injured. The characters which dis- 

 tinguish the species as compared with other Pariotichida, besides those of the teeth, 

 are the following: The interorbital width is less; the orbit large, entering the temporal 

 length 1.5 times; and the skull is narrowed posteriorly, the width being three-quarters 

 of the length, as in the Pariotichus aguti. 



"Measurtmenlt. „ 



"Total length of the skull 0.062 



Width of the skull posteriorly 041 



Interorbital width . 010 



Diameter of the orbit 016 



Elevation of the crown of a posterior superior tooth 0025 



Elevation of the crown of an anterior superior tooth . 004 



Length of posterior inferior tooth 002 



Length of anterior inferior tooth . 005 



Depth of cranium at occiput 014 



Depth ofmandibular ramus below temporal roof . .010" 



