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Show 846 MR. O. THOMAS ON THE CN°V * 17' naked, are seen on closer inspection to be furnished all oyer with scattered hairs, which give no general appearance of a hairy covering, being so fine and so nearly the colour of the skin as to be almost invisible. , ... , The tail is rather more than half the length of the body without the head, tapers rapidly from its broad and flattened base to its tip, and is thinly covered with fine bristly hairs similar in character to those on the muzzle. The feet of Heterocephalus (Plate LIV. fig. 3) are by far its most highly specialized parts, as might, indeed, be expected in so purely burrowing an animal. The anterior pair are large and strong, and the toes are much longer in proportion to the palm than is the case in Georychus. On the proximal half of the palm there are two unusually large and well-developed pads, the rest of the palm being quite smooth; in Georychus the pads are quite rudimentary. The pollex, though short, is fully developed and is provided with a minute pointed claw; the fingers are broad and flattened and are provided with similar small conical claws. The third toe is the longest, the second and fourth are about equal, and the fifth, without its claw, reaches to about the middle of the first phalanx of the fourth, and the pollex to the level of the base of the second. The hind feet, like the fore, have rather long toes in proportion to their length of sole, and in the same way the foot-pads on the sole are restricted to its posterior half, there being only three pads, two near the heel and the third at the base of the fifth toe (Plate LIV. fig. 3). The toes have much the same proportions as those on the fore feet, except that the hallux is relatively longer than the pollex, and the second toe is slightly longer than the fourth. The most noticeable character of the feet, however, and one quite unique among burrowing Rodents, is the presence of fringes of fine bristles round their edges. These bristles are not unlike those on the hind feet of the Water-Shrew (Crossopus fodiens), except that they are longer, further apart, and far finer. They grow all round the edge of each toe, and pass backwards along the sides of the feet to the wrists and ankles, although there is a gap in the series where one would suppose that they would be most wanted, viz. along the outer side of the fifth hind toe, where they are quite absent and have perhaps been worn off. The value of these cilia, by which the spread of the foot is largely increased without any increase in cumbrousness, to an animal which passes its life burrowing in a light sandy soil, is sufficiently obvious to need no comment. I am unfortunately unable to make out the number of the mammae, as, owing no doubt to our specimen having been captured out of the breeding-season, they are so small as to be only in one or two instances distinguishable from the minute warts with which the animal's naked skin is covered. The small intestine measures about 115 mm., the short rounded caecum about 12 mm., and the combined colon and rectum about 67 mm., 58 per cent, of the small intestines. The palate-ridges (Plate LIV. fig. 2) consist apparently of about |