892 



RODENTIA 



than lialf height. lli)strum ratlier long, nearly parallel-sided 

 wlien \ie\ved from abo\e, though slightly wider somewhat 

 beyond middle than at base, and tapering rather, noticeably in 

 front, its width everywhere greater than that of interorbital 

 constriction; nasals wide, abruptly rounded off anteriorly, where 

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

 narrow base, where they are abruptly truncate at level of 

 posterior extremity of nasal branches of premaxillaries, and of 

 middle f>f 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 sj^ace in front of them, twice in 

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

 eijual to that of alveolus, 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 

 Ijehind that of alveolus of m^ ; 

 hamulars simple, straight, slightly 

 diverging, widely separated from 

 bulhe ; ectopterygoid narrow, the 

 pit deep and widely open at bottom. 

 MandiT)le slender, appearing dispro- 

 portionately small for the very large 

 incisor which projects conspicuously 

 behind as well as in front, and to 

 wliich the ramus is little more than 

 a sheath ; coronoid process high, 

 slightly recurved, its anterior border rising abruptly from level 

 of front of }ii.^ ; 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 outwai'd 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 equal to greatest antero-posterior diameter ; posterior 



S/talax di'Wroiji'ie. Skull fiiiiu 

 behiiiil. Nat. size. 



