1889.] FAT-BODIES OF THE SATJROPSIDA. 609 



and Birds, owing to the backward extension of the kidneys, the fat- 

 bodies in question do practically adjoin tliem — it becomes by no 

 means improbable that the fat beneath the dorsal peritoneum pos- 

 terior to the kidneys in mammals is the homologue of, or rather 

 belongs to, the same series of deposits as the fat-bodies of the Sauro- 

 psida. 



But the habit, so to speak, of these deposits in the two groups is 

 considerably different. The Sauropsida with their backwardly situ- 

 ated 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 m position. 



IV. Some Remarks on the Function of the Sub- 

 peritoneal Fat-bodies of the Sauropsida. 



If, as above suggested, these fat-deposits in the Sauropsida corre- 

 spond 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 AmphisbaDnidse and snakes 

 (A. darwinii and Tropidonotus natrix), when still within the eggs 

 (c/". figs. 4-7, 8, 9, lOj, the fat-bodies are as well, or better, deve- 

 loped (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 re- 

 ferred to by Beddard (1, p. 103, see above pp. 606 & 607) and com- 

 pared 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 subcuta- 

 neous series. Consequently the muscularity of the layer of tissue 



