MUSCARDINUS 



585 



extending back along median line to middle of belly, but 

 anteriorly seldom covering lower lip and never extending upward 

 between ear and eye ; a family indicated, very narrow blackish 

 eye-ring ; feet ochraceous-buff, the toes sprinkled with silvery 

 hair. 



Skull. — In general form the skull differs from that of the 

 other European Muscardinidse in greater depth of brain-case, 

 particularly at its anterior portion, the posterior half sloping 

 away much more noticeably than in the allied genera, the 

 occipital region low. Interparietal usually narrowed to a point 

 at each lateral extremity. Auditory bulla essentially as in Gils, 

 but a little more inflated posteriorly, so as to be just visible 

 when skull is viewed from above. Interorbital region with 

 longitudinal median depression and slightly though distinctly 

 angular-elevated edges, the elevated regions never coming together 

 in old age. Zygomata very abruptly 

 spreading anteriorly so that the arches 

 of the two sides are essentially parallel 

 through the greater part of their extent ; 

 infraoi'bital foramen relatively smaller 

 and more nearly circular in outline than 

 in any of the other European members 

 of the family. Nasals and nasal branches 

 of preniaxillaries terminating at level 

 of front of lachrymal, the posterior 

 border of nasals usually angulate-emar- 

 ginate. Incisive foramina not widened 

 behind middle, their aspect more Murine 

 than Muscardinine. Posterior border of 

 palate emarginate to level of middle or 

 front of m", the palatine bones reduced 

 to a mere rim at front of mesopterygoid 

 space. Pterygoid fossa and ectopterygoid 



absent. Mesopterygoid fossa parallel-sided, about three times 

 as long as wide ; hamulars long and very slender, a little curved 

 upward. Mandible relatively more robust than in any of the 

 other European members of the family ; dental foramen noticeably 

 above alveolar level ; hamular process short, its point scarcely 

 rising above level of condyle ; angular region robust, very sharply 

 angled below ; a distinct vacuity above angle. 



Teeth. — In general aspect the cheek-teeth differ from those 

 of the other European Muscardinidse in their relatively greater 

 size, the flatness of their crowns, and in the more marked 

 contrasts of size and form shown by the premolar and first two 

 molars. Upper incisor with no special peculiarities. Lower 

 incisor with root extending distinctly beyond that of m^ and 

 forcing the dental foramen upward to a level slightly above that 

 of crushing surface of molar crowns. Premolar both above and 

 below small, single rooted, its crown variable in outline, but 



FIG. 115. 



Muscardinus avellanarius. 

 Nat. size. 



