SYSTEMATIC REVISION 41 



Captorhinus aguti Cope. 



Ectocynodon aguti Cope, Proc. Am. Phil. Soc, vol. XX, 1882, p. 451. (Also Pal. Bull. 35.) 



Pariotichus aguti Cope, Am. Nat., vol. XXX, 1896, p. 301. 



Pariotichus aguti Cope, Proc. Am. Phil. Soc, vol. xxxiv, 1896, pp. 444 and 445. 



Ectocynodon incisivus Cope, Trans. Am. Phil. Soc, vol. xvi, 1886, p. 290. 



Pariotichus incisivus Cope, Proc. Am. Phil. Soc, vol. xxxiv, 1896, p. 445. 



Type: A fragmentary skull showing the upper surface and the dentition of the 

 upper jaw. No. 4344 Am. Mus. Nat. Hist. Cope Coll. From Texas. 



Original description of Captorhinus aguti (Ectocynodon aguti, 1882). No. 4333 

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



"This reptile is much larger than the P. brachyops, and the anterior part of the 

 cranium has a difFerent form. The general shape of the head is much like that of 

 a rodent mammal of the genus Dasyprocta. It is rather wide at the temporal regions, 

 flat above, and narrowed and compressed anterior to the orbits. The muzzle is 

 narrowed and obtuse, and the nostrils are terminal, and are lateral and a little 

 anterior in direction. The maxillary alveolar edge is nearly straight, but the pre- 

 maxillary edge, beginning below the posterior border of the nares, descends forward 

 at an angle of 45 . Viewed from the front, the premaxillary border is a festoon, 

 strongly convex downwards, and below the anterior part of the nostril. The suture 

 separating the premaxillaries is distinct. The orbits are of moderate size, as in an 

 aguti, and invade the superior frontal plane in a slight degree. The frontoparietal 

 fontanelle is rather large. 



"The mandible is robust, and presents a short angle. It closes up behind the 

 premaxillary lobate edge. Its teeth are concealed in the specimen. The maxillary 

 teeth increase rapidly in size forwards. The premaxillaries commence smaller next 

 the maxillaries, and increase in size to the first, which is a little larger than the an- 

 terior maxillary. The crowns are weathered away. The sculpture on the maxillary 

 and malar bones consist of closely placed shallow fossae. On the posterior part of 

 the frontals there are strong ridges radiating posteriorly, and situated close together. 



"Measurements. M 



"Length of the skull to the end of the angle of the lower jaw 0.090 



Length of skull to frontoparietal fontanelle 056 



Length of skull to orbit above 026 



Lenth of ramus mandibuli 082 



Depth of skull at orbit 033 



Depth of ramus at orbit 019 



Width of skull posteriorly 068 



Width of skull between orbits 017 



Width of skull between external nares 0105 



Diameter of first premaxillary tooth 003 



Diameter of second maxillary tooth 003 



Six fossae of the malar bone 00 5 



Seven grooves of the frontal bone 00 5 



"This species is much larger than the Ectocynodon ordmatus Cope, and the 

 canine tooth has a much more anterior position." 



Description of Ectocynodon incisivus, 1886: "The muzzle is quite prominent, 

 a character somewhat exaggerated in the specimen by pressure. The nostrils are 

 large, lateral in direction, and situated close to the end of the muzzle. The orbits 

 are sub-round, of medium size, and look mainly upwards in the present condition 

 of the specimen. One of the most important peculiarities of the species is the dis- 

 proportionately large size of the first or anterior incisor or premaxillary tooth. The 

 crown is conical and nearly straight, with an acute apex slightly posterior to the 



