608 MR. G. W. BUTLER ON THE [ Dec. 3, 
generally, Thus, in the Snakes, Chelonia, Lizards, and Crocodiles, 
there is a more or less marked tendency to the separation of the 
-Inner peritoneal or visceral layer of the body-wall from the rest, the 
kidneys and fat-bodies being thus left more or less completely 
outside the peritoneal cavity. 
On the other hand, Beddard’s phrase (1, p. 105),—* the 
horizontal membrane in Varanus, which shuts off both lungs from 
the abdominal cavity,” — together with the reference which 
follows to the ‘‘membranous diaphragm” described by Martin 
(P. Z.S. 1831, p. 138), indicates that it is used to include tissue 
which shuts off the lungs from the peritoneal cavity. Here we have 
a fact of considerable interest ; and neither the dissections nor the 
transverse microscopic sections that I have made have rendered it 
plain whether, as in birds, a pleural cavity originally exists, to be 
subsequently obliterated by adhesions, or whether, as I believe to be 
the case in Testudo, the lungs are not surrounded by any part of the 
body-cavity. Whichever be the case, the separation of the lungs by 
a “membranous diaphragm ” from the peritoneal cavity which con- 
tains the liver and intestines is a feature that, so far as I know, is not 
found in any other Lizard. But, on the other hand, the lungs and 
liver are not thus separated in the Crocodiles either (cf. my paper 
“On the Subdivision of the Body-cavity &c.,” § v. this vol.). 
The preceding pages will show that in my opinion the Monitors 
bear no special resemblance to the Crocodiles, so far as the relations 
of the fat-bodies and the spaces and membranes about them are 
concerned. The shutting off of the lungs from the liver, while sug- 
gesting the condition in the birds, distinguishes them from the 
Crocodiles, and, in the absence of developmental data, it may be 
perhaps just as well explained by a reference to Testudo’. 
Again, seeing that some striking differences exist as to the sub- 
division of the body-cavity in the other Lizards (cf. the case of the 
Teiidze above, Plate XLVIII. and text, p. 466), it appears to me 
doubtful whether, in our ignorance of the developmental history, the 
shutting off of the lungs from the peritoneal cavity in the Varanidee 
has much or little significance for the systematist. 
III. SusrerironeaL Fat or MAMMALS. 
To turn to animals outside the Sauropsida, we find among 
mammals deposits of fat on either side of the bladder (e. g. Kitten, 
Guinea-pig, Hedgehog, young Kangaroo). It is impossible in some 
cases to definitely mark off the fat in this position from that which 
passes forwards on the dorsal side to the kidneys; and both are 
supplied by branches from the femoral artery (Guinea-pig). If this 
vessel is the homologue of the femoral artery of Sauropsida, which 
supplies the fat-bodies (Lizards)—seeing that in Lizards, Crocodiles, 
? Emys, in which the lungs only partly project into the body-cavity, would 
seem to stand as a link between Zestudo and the majority of animals that have 
the lungs fully projecting into the ccelom, and to show that even such a striking 
feature as the exclusion of the lungs from the body-cavity may be of comparatively 
little systematic importance. 
