610 MR. G. W. BTJTLER ON THE [DcC. 3, 



between them and the abdominal cavity is accounted for by it being 

 a part of the muscular abdominal wall, separated from the outer 

 layer by the spaces surrounding the subcutaneous fat. 



In birds, again, besides the subperitoneal fat of the " omentum," 

 we have subcutaneous fat along the whole length of the trunk, on 

 each side of the thorax and abdomen, and tbis extends on to the 

 legs. This series of deposits is well seen in the unhatched chick. 

 Doubtless subcutaneous fat is found in the above-named groups, 

 in places besides those indicated, which, however, are those which 

 I have specially studied in examining the interesting questions 

 raised by Beddard's papers; but, as a general rule, not only in the 

 above groups but also in mammals such subcutaneous fat is charac- 

 teristic of the morphologically ventral face of the body rather thau 

 of the dorsal. Moreover the deposits in mammals seem largely to 

 correspond with those in the Sauropsida. Nor is the degree of 

 constancy of distribution of these suisperitoneal and subcutaneous 

 fat-deposits which exists surprising, if, as I think, this distribution is 

 connected with that of the blood-vessels ^ 



VI. On the Fatty "Spleen " of the Crocodiles. 



I should like to draw attention to a curious body which seems very 

 constant in all specimens of Crocodile. It is situated on the right 

 side and is attached dorsally by a distinct peritoneal ligament, which 

 extends obliquely from near the externo-posterior extremity of the 

 right liver-lobe, to a spot more median than the anterior end of 

 the reproductive gland {cf. above, Plate XLIX. fig. 43, with the 

 ' ' seeker ' ' represented) . 



The only references to this body that I have seen occur in 

 Hunter's ' Essays and Observations,' edited by Owen (vol. ii. 

 p. 338), and in Owen's papers in this Journal for 1831, pp. 141 

 and 16'J. Hunter describes it as the spleen. Owing to the intestines 

 being much folded, it is quite possible that this distinctly dextral 

 body may be in the morphologically normal position of the spleen, 

 i. e. suspended on the left side of the median membrane that sup- 

 ports the alimentary canal. But, on the other hand, as Hunter 

 remarked {loc. cit. p. 339), there is " an oblong dark body placed in 

 the root of the mesentery;" he says further on, " 1 imagine this is 



1 The ventral region of the body above referred to is, of course, tlie region 

 where the mammary glancl.s are apt to occur. These are generally allowed to 

 be specialized cutaneous (sebaceous) glands, and they are described by Dr. 

 Creightou (Journ. Anat. & Phy.s. vol. si.) as arising in intimate association with 

 deposits of fat. Now th.^ femoral glands of Lizards open on the ventral side of 

 the abdomen and thighs, and are frequently found surrounded by fat, and in 

 microsco]5ic sections strongly resemble sebaceous glands. Gegenbaur has 

 recently shown that in the Monotremes the mammary glands do not conform 

 to the type common to all the higher Mammalia, and yet \^e place the two 

 types of gland in the same category ; may it not somewhat similarly be sug- 

 gested that in these quasi-sebaceous glands of lizards, and deposits of ventral 

 subcutaneous fat, so commonly represented in Birds and Reptiles, we have the 

 Sauropsidan modification of that which in Mammalia has developed into such 

 typical structures as the mammary glands and the sebaceous glands in associ- 

 ation with which the characteristic hair occurs ? 



