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Show 224 EXPLOUATION OF 1'HE OANONS OF THE COLORADO. jaw, about half-way from nose to eye, ju t uudemeath the whisker-patch, and curves loosely around the side of the head to the angle of the jaw. The general outline of the orifiee i.s semicircular (or rather semi pyriform, since the broadest part sags down a little) ; the inner border being the proper integu-ment of the side of the head. The lining of the sac is ordinary integument, of rather more delicate texture; it is clot.hetl with fine fur. On the side next the head, the ordinary fur of the parts makes directly into the pouch; on the outside, the fine fur continues to the brim, where it is met by the ordinary external pelage. Between the two layers of skin rests a thin bed of muscular fibers (perhaps a modified platysma myoides), serving for such contractile movements as the receptacle may be susceptible of: But the connection between the folds of skin is so slight and loo c that the pouci1 may, with little force, be turned completely inside out, though it does not appear that this ever occurs in life. A full-sized pouch will admit three fingers as far as the fi n~t joint. The small eyes are situated midway between the nose and cars, below the line between these two; and, if anything, they are rather nearer the latter than the f(mncr. 'rhe ears have been described in varying terms, leaving a doubt whether there was an auricle or not; but it is proper to say that the auricle is obsolete. rrhe large circular orifice of the meatus externus is surrounded by a raised brim, rather thicker, if not higher, behind than before, and, as such, constituting a rudimentary pinna; but there is nothing to be called a flap (which is something that may be turned over). The large, strong, and eminently fossorial fore feet recall those of the mole in some respects, though they occupy the usual position with reference ~o the. axis of the limb-sole rlownward instead of tilted over. The hand Itself 1s shorter than the hind foot· but the immense claw 'h . . ' · s reverse " e pro-portwn of the two as a whole. The palm is broader than the sole, and perfectly naked. At the juncture with the wrist, it presents two great movable .c allous tubercles, which probably have a bea' rin{Jo' upt)n th e great f'o rce of fl ex-wn. ~f the member; otherw~se tl~e palm is flat, devoid of special pads or cal-lo. tbes, and may be thrown Into mdeterrninate rugre or sulci, according to the movements of the parts. There are five digits, whose relative lengths arc nearly the same as those of the claws they respectively bear. All the claws ' OOUES ON Gl!JOMYS AND TIJOMOMYS-G. HURSARIUS. 225 excepting the fir~t oue, are longer thau their respective digits; they arc much compressed, siuglc-edgcd underneath, curved, and acute. Their tips are regularly graduated in position with decreasing disparity from 3d to 1st; 3d- 4th- 2d-5th-lst; the 3d being much the largest, the 1st a mere stump. The back of the hand is clothed with rather bristly hairs, which fall as a fringe · · over the sides of the hand, and of the individual digits as well. As usual in cases of excessive growths of any kind, these great claws of the hand vary a good deal in size and shape, according to the age and vigor of the animal-in other word.,, according to the degree of use to which they art: put. The hind foot is uot remarkable, having un ordinary murine character. The sole is perfccUy naked, like the palm, and devoid of special pads or tubercles; the sl\in being everywhere smooth. The toes are short; the claw,s still shorter, weak, excavated unclerncath (lilw a badger's), little curved, and rather acute. The 3d is longest; then come 2d-4th-lstr-5th; the digit of the latter being a mere stump, and that of the 1st too short to carry the tip of its claw opposite the base of the 4th. The tail has an unfinished, or rather neglected, appearance, a:s if it were of no particular use. It is remarkable, however, for appearing to spring from a peculiar conical backward prolongation of rump, so t hat it is difficult to determine its true base. This enlarged bm~al portion is clothed like the rest of the body. From its apex, the tail contin ues with a shorter and more scanty furring. The tail is rather thick (in comparison with allied rodents) and somewhat quadrangular, the flattening of the under side being especially noticeable ; it tapers gradually to an obtuse t ip. It is perhaps rather unusually variable in length, averaging in its scant-haired portion about one-t hird of the length of head and body. The conical prolongation of the body above mentioned is that portion which protrudes beyond the ischia, which may be plainly felt on either side ; and on its under side appear the orifices of the digestive and genito-urinary systems, in close juxtaposition, and both directly at the base of the tail proper. In the rutting-season, however, the topography of the parts is changed, owing to the great distention of the perinreum from the tu rgid organs within. In the fe male, there arc three pair of teat - two inguiual, near together along the inside of the thighs; and auot.her pair, pectoral, at a 29 OOL |