382 BULLETIN UNITED STA'I'ES GEOLOGICAL SURVEY. [Vol.Yl. 



drawn from the skeleton generally can be derived from my material 

 and are now given. 



The nasal bones are wide, and the suture which separates them both 

 from the frontal is concave forwards. The median frontal suture is 

 persistent. The ascending portion of the premasillary, which attains 

 the frontal, is ve ry narrow. The superior half of the facial plate of the 

 maxillary bone is sharply rugose with reticulate ridges, but whether 

 perforate or not I cannot certainly determine. The foramen infraorbita le 

 is small and round, and issues below the reticulate portion of the max- 

 illary. The otic bulla is compressed globular, with very thin walls. The 

 meatus is large and has i)rominent lips, which open upwards. The 

 mastoid is coossified with the bulla, and extends with a dense surface 

 from behind to above and in front of the meatus. The incisive foramina 

 are very large, enter the maxillary bones deeply, and are confluent pos- 

 teriorly. The palate may be said to extend to the last molar, but there 

 is a deep though narrow median posterior emargination. 



The distal extremity of the humerus is not so extended transversely 

 as in Ischyromys, and exhibits a moderate epicondyle. The inner flange 

 of the condyles is well developed, and on the posterior face it is supple- 

 mented by a flange of the external edge of the condyles, which is as promi- 

 nent or even more so, forming an intertrochlear crest. The arterial 

 canal is inclosed by a slender bridge, and opens on the inner side above, 

 and anteriorly below. In an ulna supjDosed to belong to this genus the 

 coronoid process is elevated. The radial facet forms a narrow transverse 

 plane, nearly divided by a wide anterior emargination. The shaft is 

 compressed vertico-obliquely. A radius exhibits a transversely oval 

 humeral face of the head somewhat angulate at a superior and an 

 infero -lateral extremity, which are diagonally opposed to each other. 

 Beyond the middle the shaft becomes wider, and is flattened obliquely. 



The peduncle of the ilium has a triangular section, the anterior face 

 being the narrowest, and inclined at a little more than a right angle to 

 the interior face. It expands but little at the sacral extremity, and the 

 crest is very short. The external angle of the peduncle is very promi- 

 nent and runs into the anterior extremity of the crest, from which pro- 

 ceeds also the more obtuse angle which is continuous with the pectin- 

 eal line. A third longitudinal angle is seen en the middle of the external 

 side of the sacral extremity, which is not continued on the peduncle. 

 There is a prominent tuberosity on the median or first-described angle, on 

 the peduncle which may or may not be homologous with the anterior 

 inferior spine. There is no tuberosity on the inner bounding angle of 

 the inner face as is seen in Gymnoptychus. The pubis leaves the ilium 

 at right angles. Acetabulum nearly round. 



The femur has well developed great and little trochanters, and a third 

 trochanter, which rises from the shaft in line with the inferior border 

 of the little trochanter. The fossa of the great trochanter is well marked. 

 The head is not separated Irom the great trochanter by a deep emargi- 



