MORPHOLOGICAL REVISION 



93 



appearance of the teeth does not warrant the description given by Cope in his ana- 

 lytical table of the genera of the Captorhinidce (Pariotichidee). He says the palatal 

 and splenial teeth are compressed and that the jaw teeth are equal and acute. 

 No splenial or palatine teeth can be seen 

 and the condition of the specimen does not 

 show that the jaw teeth are equal; there was 

 at least one elongated tooth in the anterior 

 part of the maxillary series. 



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



Characteristic specimens: Nos. 4334, 

 4328, 4424, all Am. Mus. Nat. Hist. Cope 

 Coll.; No. 642, University of Chicago. 



The following description of the genus 

 is based on all the specimens, as the specific 

 differences are minor and, as stated before, 

 even of doubtful value in one or two cases. 

 The best-preserved specimen of the skull is 

 that described by Cope as Pariotichus aguti, No. 4334 Am. Mus. This has also the 

 clavicles and interclavicle, the humerus of the right side, and the first few vertebra?. 



The general shape of the skull, as described by Cope, is elongate, flat on the 

 top, with a decurved snout and a wide temporal region. 



Premaxillaries: These are small and hardly appear on the upper surface of the 

 skull; each one carries four teeth. The median pair is the largest, the others dimin- 

 ishing rapidly and regularly to the maxillary-premaxillary suture. 



Fig. 38.- 



75 aguti 



No. 4334 Am. Mus. 



a, Lower view of skull; b, lower jaw. The posterior 

 ends of the lower jaws are attached to the skull, p! , 

 palatine; pi, pterygoid. 



Fig. 39. — Captorhinus angusiiceps. X i- No. 4457 Am. Mus. 



a. Upper view of skull, n, nasal; /, lachrymal; plf, postfrontal; pf, prefrontal; po, postorbital; /, frontal; j, jugal; 



sq, squamosal; p, parietal; so, supraoccipital plate; t, tabulare. 



b. Lateral view of same specimen shown in a. 



c. Posterior surface of skull, p, parietal; t, tabulare; so, supraoccipital plate; so', supraoccipital; exo, eioccipital; 



qj, quadratojugal; sq, squamosal; pt, pterygoid. 



The nasals are large bones reaching back nearly to the anterior edge of the 

 orbit and forming the inner edge of the nares. 



The lachrymals form the anterior border of the orbit and reach forward to the 

 nares, forming its posterior border. 



The prefrontals form the upper anterior border of the orbit and lie between 



