CEICBTUS 



599 



noticeably upward posteriorly, its anterior half with median 

 groove, the backward extension of that occupying most of 

 basisphenoid. Auditory bulla rather large, evenly inflated, not 

 in contact with paroccipital process, its greatest diameter 

 oblique ; meatus large, without tube or lip ; a distinct depression 

 near middle of bulla parallel with meatus ; greatest diameter of 

 bulla about three times anterior width of basioccipital. Inter- 

 orbital region narrow, with distinct median furrow and raised 

 edges, the margin slightly but evidently angled posteriorly ; 



Fia. lis. 

 Cricetus cricetus. Nat. size. 



behind angles the ridges and furrow pass gradually into the 

 narrowest anterior portion of flat median area of brain-case. 

 Zygoma heavy but without special features, very gradually 

 spreading, so that greatest zygomatic breadth is at front of 

 glenoid region ; anteorbital foramen wide above, narrow and 

 slit-like below, the well developed external plate of canal plainly 

 visible when skull is viewed from above, its anterior border 

 nearly perpendicular. Rostrum very heavy, its greatest width 

 at about middle, decidedly wider than interorbital region and 

 more than half as wide as brain-case ; width at middle decidedly 



