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Show 1866.] ON T H E A N A T O M Y O F T H E C R E S T E D AGOUTI. 385 oblong pads, situated at the base of the innermost toes, the smaller one being internal, having at a distance of less than half an inch behind it a trace of a third pad. Beneath the metatarsals there is a good deal of transverse wrinkling, and underneath the digits the same scaly appearance as in the digits of the fore foot (fig. 1, C). The Guinea-pig has a hind foot in some respects very like this ; but the pads are comparatively larger, and the external one much the larger of the two ; the three toes also are of nearly equal length (fig.l.D). The Hare has four toes, with fur on the sole ; and when the fur is removed neither pads nor wrinkles are to be distinguished. In the length and shape of the sole and toes the Hare's foot approaches that of the Agouti's ; but the number of digits, with the other differences, are marks of the separation between Lepus and the two genera of the Hystricidar. MORBID APPEARANCES. Those exhibited on opening the visceral cavities were the following :-Congestion of the lungs, more particularly the lobes of the right one. In both lungs, moreover, were innumerable specks of melanotic deposit, each spot not above the size of a pin's head, but the whole giving to the pulmonary tissue the characteristic appearance of incipient melanosis. All the other viscera, as well as the brain, seemed healthy; but there was a more than natural effusion of serum in the cavity of the abdomen. VISCERA AND GENERATIVE ORGANS. A good account of the viscera of Dasyprocta acuschy (Illig.) has already been given by Professor Owen*; and, a few years later *%(1834), in some notes also read before this Society, Mr. Rymer Jones'f described with considerable minuteness those of Dasyprocta aguti, Illig. A complete redescription may therefore be considered unnecessary. Prof. R. Jones mentions that, in the specimen of D. aguti dissected by him, the stomach had a remarkable constriction between its cardiac and pyloric orifices, which gave it the appearance of consisting of two distinct cavities. Our observation of this viscus in D. cristata agrees with that of Prof. Owen, who found it in D. acuschy altogether simple and without such a contraction. The shape and relative position of the intestinal tract in D. cristata resembles the description given by these authors of the species dissected by them. But we found in it that the small intestines were about 4 feet shorter than in D. aguti, namely 208 inches in total length. The large intestines, on the other hand, measured 45 inches, being thus almost double the length of the same in D. aguti according to Prof. R. Jones. The caecum also differs from that of D. aguti, being both longer and wider- 10 inches in length, and about 4 inches in circumference. * P. Z. S. 1830-31, p. 75. t P. Z. S. 1834, p. 82. |