LEMMUS 187 



strong, simple claws of large size, though distinctly smaller than 

 those of the fingers. Soles densely clothed with stiffened hairs 

 like the palms. Plantar tubercles reduced usually to four 

 vestigial pads occupying their normal positions at the bases of 

 contiguous digits.^ Tail shghtly shorter than the hind-foot, 

 robust and clavate, its diameter greater in the terminal third 

 than at the base, clothed with long stiff hairs which do not com- 

 pletely conceal the rather narrow and ill-defined annulations ; 

 terminal pencil about half the length of the caudal vertebrae. 

 Mamma?, 2 — 2 = 8. 



Skull (Fig. 76) massively built, somewhat depressed, and very 

 broad ; with long, stout and sharply deflected rostrum ; widely 

 and abruptly spreading zygomata; short, broad and depressed 

 braincase which appears to be pressed forwards, encroaching 

 upon the orbito-temporal vacuities to a greater extent than 

 in other members of the subfamily (Myopus alone excepted) ; 

 the post-glenoid region strikingly shortened. Nasals more 

 or less broadly expanded anteriorly, where they end shghtly 

 behind the front faces of the incisors ; behind they terminate 

 in line with the premaxillaries, shghtly in front of the anterior 

 margins of the orbits. Zygomata very strong and heavy, given 

 off from the base of the rostrum at right angles, widely expanded, 

 the greatest zygomatic breadth occurring in front on the maxillary 

 portions of the arches and equal to about 68% of the condylo- 

 basal length ; each zygoma formed for more than half its length 

 by the maxillary zygomatic process which expands distally 

 into a broad fork clasping the broad but short jugal; upper 

 border of jugal boldly convex, the jugal and maxillary process 

 together forming a broad, central, fusiform expansion of the 

 zygoma ; the outer surfaces of these central expansions are 

 obhquely inclined and sharply convergent dorsally, so that 

 they partly roof the orbito-temporal vacuities and appear broadly 

 in the dorsal view of the skull ; the squamosal root of each 

 zygoma is much lighter, its lower border being, however, widened 

 and flattened as a facet for the origin of the posterior portion of 

 the masseter mediahs muscle, and it is given off from the side 

 of the braincase at a right angle. Infraorbital canal nearly 

 normal; its inferior slit-hke portion somewhat reduced by the 

 alveolar capsules of the upper incisor and m^ ; its wider ujjper 

 portion transmits a small slip of the masseter medialis as usual, 

 the origin of the muscle just impinging upon the hinder and 

 lower edge of the ascending branch of the premaxilla ; the outer 

 wall of the canal, giving origin to the masseter lateralis, is very 

 broad and in consequence of the abrupt anterior expansion of 



' Usually there is no trace of the tarsal pads, but in the Lemming 

 mentioned in the precedintr footnote there are five vestigial plantar tubercles, 

 the fifth being jjostero-intemal and representing the inner of the two tarsal 

 pads normally present in Jluridoe. In this specimen both the palmar and 

 plantar tubercles, although very small, are not concealed by the dense 

 hair, and therefore they cannot be said to be altogether functionless. 



