ZYGOGEOMYS. 331 
Ne) 
4 
1 
kull long and narrow; maxillary and squamosal branches of 
zygoma in contact above jugal, which is mainly external; rostrum 
long and narrow; orbitosphenoids large, and with the exception of 
a foramen at apex, close the upper part of sphenoidal fissure, and 
ankylosed with the alisphenoid; mesethmoid quadrangular; upper 
incisors bisulcate, chief sulcus on median line, minor on inner con- 
vexity. First and second upper molars with two enamel plates 
FiG. 63. ZYGOGEOMYS TRICHOPUS. 
No. so107 U.S. Nat. Mus. Coll. Nat. size. 
