536 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. 1 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-like 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 is 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 Chirogahus and certain 

 species of Lemur possess to the inner side of it a bundle of long 

 and stiff bristles associated with unusually large sebaceous 

 glands ; these structures are, of course, not homologous with the 

 gland of the arm of Hapalemur, as they coexist in the same 



"On some Points in the Structure of Hapalemur griseus " Proc. Zool. Soc. 

 1884, p. 301. 



