892 



equal to that of alveolus, 



tliau lialf lieight. liostruiu ratlier long, nearly iiacallel-suled 

 wlieii viewed from above, though shghtly wider somewhat 

 beyond middle than at base, and tapering rather noticeably in 

 front, its width everywhere greater than that of iuterorbital 

 constriction ; nasals wide, abruptly rounded off anteriorly, where 

 they project so as to conceal incisors, tapering gradually to a 

 narrow base, wliere they are abruptly truncate at level of 

 posterior extremity of nasal branches of premaxiilaries, and of 

 middle of infraorbital foramina ; in lateral view the rostrum is 

 strongly cuneate, its least depth, immediately behind incisors, 

 contained about 2| times in that at alveolus of m^ ; incisive 

 foramina very small, slit-like, at level of anterior border of 

 zygomatic root, their greatest diameter contained about six times 

 in diastema (three times in space in front of them, twice in 

 that behind). Palate very narrow, its least breadth scarcely 



its surface marked by a median 

 ridge and two lateral grooves ; pos- 

 terior termination of palate simple,, 

 without pits or changes of level ; 

 mesopterygoid space parallel-sided, 

 about twice as long as wide, squarely 

 truncate anteriorly at level a little 

 behind that of alveolus of m^ ; 

 hamulars simple, straight, slightly 

 diverging, widely separated from 

 bulla5 ; ectopterj^goid narrow, the 

 pit deep and widely open at bottom. 

 Mandible slender, appearing dispro- 

 portionately small for the very large 

 incisor which projects conspicuously 

 behind as well as in front, and to 

 which the ramus is little more than 

 a sheath ; coronoid process high, 

 slightly recurved, its anterior border rising abruptly from level 

 of front of 7n.2 ; articular process low, its base distorted by the 

 shaft of incisor ; angular process with rather long, strongly 

 convex lower border, its free portion short, abruptly curved 

 outward, not extending behind level of condyle ; between 

 articular and angular processes and somewhat in front of them 

 projects outward and upward the encapsuled base of the incisor, 

 rising in fully adult individuals to a height intermediate between 

 that of articular and coronoid processes, and forming the most 

 conspicuous single feature of this part of jaw. 



Teeth. — Incisors large and heavy, molars small, the contrast 

 greater than in any other European rodent. Upper incisor strongly 

 curved, the exposed portion nearly vertical, the root forming a 

 slight protuberance at side of palate immediately in front of 

 first molar ; shaft not compressed, the width of flat anterior face 

 nearly ecjual to greatest anteroposterior diameter ; posterior 



Fig. 183. 



S'palax ddlbrogese. Skull from 

 behind. Nat. size. 



