NO. 1554. .1 NEW HORNED RODENT— aiDLKY. 629 



iest. Tibia greatly moditied and twisted laterally, throwing the long 

 axis of the foot inward at nearly a right angle to the fore-and-aft plane 

 of the leg. 



Measurements for cotiiparison iritJi those given bij Matthew for Ceratogaidtis. 



Mm. 



Length of skull 80 



Width across arches 64 



Width of occiput 75 



Height of horn core 82 



Length of horn core at base 17 



Conjoined width of horn cores 2S 



Width across postorbital processes of frontals 27 



Width across postorbital ridges (at narrowest point) 20 



Depth of zygomatic art'h beneath orljit 10 



Length of diastema 23 



Length of three upper cheek teeth 20 



Length of upper p* 13 



Width of upper p* 8 



Length of lower jaw 62 



Depth of lower jaw beneath molars 19 



Height of lower jaw, angle to tip of coronoid jirocess 44 



Length of three lower cheek teeth '. 20 



Length of lower p^ 15 



Width of lower p4 _ 7 



7)< tailed desci'ipfion (DidcovqHii'lmns. — The skull viewed from })elow 

 has about the proportions of that of Ce7\tt()(janlux, but the broader and 

 more extended nasals, the more l)ackwardly placed horn cores, and 

 more broadly expanded occiput give to the upper part of the skull a 

 markedly ditierent appearance. The top of the cranium (Plate LIX, 

 lig. h) is broad and saddle-shaped, the postorl)ital crests converging but 

 slightly as they run ))ackward to the occiput. The zygomatic arches 

 are heavy and deep, with prominent postorhital processes. The post- 

 orbital processes of the frontals are less prominent than in Ceiuitogau- 

 las or Myhiganhis. The infraor])ital foramen is moderately large, 

 piercing the broad anterior border of the zygomatic arch in much the 

 same maimer as in tiie existing genus Ajdodontt'a. The squamosal 

 expands postero-externally, sending a process outward and downward, 

 which becomes visible on the occiput partially inclosing the posterior 

 portion of the mastoid, as in Aplodontia. This character is also observ- 

 able in the Spalacidic and some members of the Sciurida*. The base of 

 the skull (Plate LX, tig, 1) shows some striking resemblances to that of 

 Aplodontia (Plate LX, tig. 2) especialh^ in general form and propor- 

 tions and the arrangement of the foramina. The wings of the ptery- 

 goid and alisphenoid are sul)equal in size, with a shallow intervening 

 fossa. The posterior opening of the alisphenoid canal is a well-rounded 

 foramen, opening downward. The foramen rotundum and foramen 

 ovale pierce the alisphenoid bone in Epujanlux and Aplodontia^ and 



