610 MR. G. W. BUTLER ON THE (Dec. 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 this 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 than 
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 subperitoneal and subcutaneous 
fat-deposits which exists surprising, if, as I think, this distribution is 
connected with that of the blood-vessels’. 
VI. On tHe Farry “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 169. Hunter describes it as the spleen. Owing to tke 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. cié. p. 339), there is “ an oblong dark body placed in 
the root of the mesentery;” he says further on, “ I imagine this is 
1 The ventral region of the body above referred to is, of course, the region 
where the mammary glands are apt to occur, These are generally allowed to 
be specialized cutaneous (sebaceous) glands, and they are described by Dr. 
Creighton (Journ. Anat. & Phys. vol. xi.) as arising in intimate association with 
deposits of fat. Now the femoral glands of Lizards open on the ventral side of 
the abdomen and thighs, and are frequently found surrounded by fat, and in 
microscopic 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 we 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 ? 
