GLIRES OF THE SANTA CRUZ BEDS. 397 



whole width of the humeral trochlea ; the shaft is quite stout, antero-pos- 

 teriorly compressed and of transversely oval cross-section, and has a de- 

 cided forward curvature. The ulna has a relatively short olecranon, much 

 as in Capromys, a very broad coronoid process and a wide sigmoid notch, 

 which articulates with the posterior side of the humeral trochlea ; the shaft 

 is quite stout, laterally compressed and arched forward, with an obscure 

 channel on the outer side of the proximal portion. 



Nothing is known of the carpus and very little of the metacarpals and 

 phalanges, which are represented by very fragmentary material. It is 

 apparent, however, that the manus is somewhat larger and heavier in pro- 

 portion to the pes than is the case in Myocastor. A single imperfect 

 ungual phalanx resembles that of Agouti, being more depressed and less 

 pointed than in the former, and, seemingly, having no cleft at the tip. 



The pelvis is elongate ; the ilium has a broad and ill-defined peduncle, 

 which expands quite abruptly into the anterior plate ; this anterior expan- 

 sion is quite unlike the trihedral ilium of Myocastor, having somewhat 

 more the shape seen in Capromys, but is considerably broader than in the 

 latter; a resemblance to Agouti is in the prominent development of the 

 ilio-pectineal process, as also in the division of the gluteal surface by a 

 distinct longitudinal crest. The ischium is incomplete in all of the spec- 

 imens ; so far as preserved, its post-acetabular portion is quite slender and 

 laterally compressed, slightly increasing posteriorly in the dorso-ventral 

 diameter ; the obturator foramen is evidently large. 



, The femur is large, much surpassing the humerus both in length and 

 thickness ; the head is rather small and set upon a constricted neck, and 

 the great trochanter is thick and heavy, but rather short, making the notch 

 between itself and the head no deeper than in Capromys ; the digital fossa 

 is large and very deep ; the second trochanter is much reduced and there 

 is no trace of the third. The shaft is stout and somewhat compressed 

 laterally ; the distal end is heavy, though the condyles are not prominent ; 

 the rotular groove is narrow, but has elevated borders and is continued 

 very far dorsally, resembling that of Agoidi. The patella is quite large, 

 especially in width, but antero-posteriorly compressed and with a small 

 diameter in that direction ; it thus differs much from the massive patella 

 of Agouti and is more like that of Capromys. 



The tibia is not ankylosed with the fibula and is a very heavy bone, of 

 almost the same length as the femur ; proximally, the shaft is trihedral, 



