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Show 1889.] FAT-BODIES OF THE SAUROPSIDA. 609 and Birds, owing to the backward extension of the kidneys, the fat-bodies in question do practically adjoin them-it becomes by no means improbable that the fat beneath the dorsal peritoneum posterior to the kidneys in mammals is the homologue of, or rather belongs to, the same series of deposits as the fat-bodies of the Sauropsida. But the habit, so to speak, of these deposits in the two groups is considerably different. The Sauropsida with their backwardly situated kidneys, renal-portal system, and anterior abdominal veins, have these fat-masses either confined to the region just in front of the pelvic girdle, or extending right along on the ventral side as far as the stomach and liver ; whilst in Mammals, where the vascular system is different, they are mainly dorsal in position. IV. SOME REMARKS ON THE FUNCTION OF THE SUBPERITONEAL FAT-BODIES OF THE SAUROPSIDA. If, as above suggested, these fat-deposits in the Sauropsida correspond to those, so common in Mammalia, behind the kidneys, there would appear to be no more reason to seek a special function for them in one group than in the other, as some observers have done for the Reptiles. These bodies, like the liver, can be regarded as stores of food-matter on the course of large blood-vessels, and of course they will be drawn upon whenever need arises-whether in the " winter sleep," as appears to have been usually assumed, or in the production of large masses of yolk for the eggs, or at any other time when food may be unattainable. It should be noted that in both Amphisbsenidae and snakes (A. darwinii and Tropidonotus natrix), when still within the eggs (cf. figs. 4-7, 8, 9, 10), the fat-bodies are as well, or better, developed (proportionally) than at any subsequent period of life. This, together with the fact that there seems no marked difference in their size in the two sexes, would seem to show that their function is a general one and not specially related to reproduction, as has been suggested. V. ON CERTAIN SUBCUTANEOUS FAT-DEPOSITS. In Lizards we have fat ventral to the pelvic girdle (between it and the skin) and extending along the under part of the thigh and surrounding the "femoral glands" (when present). This seems to have no continuity with the subperitoneal fat-bodies above described. In the Crocodiles both the subcutaneous and the subperitoneal fat seem to be fairly well developed, the former being separated from the abdominal cavity by a muscular tract, which I think is that referred to by Beddard (1, p. 103, see above pp. 606 & 607) and compared to what he terms the " horizontal membrane " in Monitors. It appears to me, however, that only the lateral fat-masses of Crocodiles correspond to the ventral subperitoneal " fat-bodies " of the Lizards, and that the ventral deposits in Crocodiles belong to the subcutaneous series. Consequently the muscularity of the layer of tissue |