5 36 ARM GLAND OF HAPALEMUR CHAP. 
detail it may be stated generally that the anatomy of the brain of 
this group confirms the classification which is adopted in this 
work. 
A curious feature in the anatomy of the Lemurs, which they 
share with animals so remote from them in the system as the 
Edentata, is the breaking up of some of the arteries of the limbs 
to form retia mirabilia ; nothing of the kind is known among 
the other Primates. 
Perhaps the most remarkable difference between the Lemurs 
and the Anthropoidea, which are really in many respects more 
closely allied than might be inferred from the above summary of 
differences, is in the structure of the placenta. The Lemurs agree 
with the Ungulates in having a non-deciduate placenta. 
A curious feature confined to the sub-family Lemurinae was 
first discovered by myself in Hapalemur griseus.’ On the 
forearm (see Fig. 258) is an area of hardened skin, which is 
raised into spine-like processes. Fully developed, this organ is 
characteristic of the male, the area being marked off in the 
female, but without the spiny outgrowths. On removing the 
skin a gland about the size and shape of an almond is brought 
into view. In other Lemurs there is no modified skin, but a 
small tuft of particularly long hairs, which are also present in 
Hapalemur, and a small gland beneath the skin. The gland of 
Hapalemur may be comparable with a tract of hardened skin in 
Lemur catta, which projects to a large extent and has been spoken 
of as a “ climbing organ.” 
An almost exactly similar tuft of spine-lke outgrowths exists 
upon the lower end of the ankle of Galago garnetti. The spines 
are black and bent, just as they are in Hapalemur. There 
appears also to be a gland. This structure 1s not universal in 
the genus Galago any more than is the patch of spines in the 
genus Hapalemur. 
In addition to this gland and to the patch of spines which 
cover it, the same Lemur as well as Chirogaleus and certain 
species of Lemur possess to the inner side of it a bundle of long 
and stiff bristles associated with unusually large sebaceous 
elands; these structures are, of course, not homologous with the 
sland of the arm of Hapalemur, as they coexist in the same 
' “On some Points in the Structure of Hapalemur griseus’ Proc. Zool. Soe. 
1884, p. 301. : 
