MURIDH®—ARVICOLIN AX—FIBER. 253 
The stout zygomata do not dip down nearly to the palatal plane; the 
maxillary plate supporting them in front is large; behind, they curve up to 
the squamosals with moderate angularity. The arch is expanded in the 
middle, much as in the Lemmings and the stouter Arvicolas, chiefly by the 
laminar character of the jugal at this point; but the jugal is a mere splint, 
not forming by itself any part of the continuity of the arch, for the squamosal 
and maxillary spurs are absolutely in contact. This is a strong point of Fiber, 
for in other Arvicolines these spurs, however closely approximated, do not 
suturally unite. The parietals and interparietal are at a minimum size, coin- 
cident with the encroachment of the highly developed squamosals; behind, 
the squamosal vacuities are large; in front, this bone protrudes as an angular 
process into the orbital space, but this is merely an exaggeration of the 
smaller protuberance of other Arvicoline. The constriction of the frontal in 
the interorbital region is at a maximum, the skull being here obviously nar- 
rower than the rostrum. The nasals and intermaxillaries are of about equal 
lengths; neither extend beyond the anterior root of the zygoma. In the 
adult, the occipital bone shows no trace of its elements; the paroccipital 
processes are lengthened spurs; the upper border of the bone forms, with 
the continuous squamosal border, a strong sinuate crest, separating the 
parietal from the occipital plane. The foramen magnum is usually emarginate 
superiorly. The auditory bulle are not peculiar. The palate ends behind 
opposite the middle of the last molar as a doubly emarginate shelf, showing 
a median azygos protuberance with a fossa on either side; it shows likewise 
other lateral fossze or canals along its surface. ‘The incisive foramina are 
relatively short and constricted; they rarely, if ever, reach to opposite the 
molars behind, nor more than two-thirds the distance thence to the incisors 
in front. The rostrum is tamid and obtuse, the nasals falling far short of a 
perpendicular tangent to the incisors. In all this, it will be observed, Fiber 
shows slight specialization of ordinary arvicoline characters. 
Externally, however, the modifications are stronger, in face of special 
habitus. The under fur is even more woolly than in the Lemmings, and the 
pelage is further conspicuous for the many stiff and glistening hairs with 
which it is beset ; besides these, the antibrachium has a peculiar fringe of still 
stiffer bristles. The sides of the hands and feet are likewise fringed with 
hairs, but the soles and palms are perfectly naked ; above, these members are 
closely pilous with very short adpressed hairs. The palms have five tuber- 
