82 THE GENERAL ANATOMY OF THE LEMUROIDEA [SECT. A 



as described in (ii) above. The tendon to the hallux is not 

 perforated, but it accompanies the tendon of the M. flexor hallucis 

 longus. The Mm. lubricales are not primarily associated with the 

 M. flexor tibialis (flexor digitorum longus). 



(iv) The M. flexor hallucis longus (flexor fibularis) arises from 

 the tibia as well as from the fibula, and terminates in a tendon of 

 great strength which passes through a tunnel beneath the entocunei- 

 form bone. Beyond this the tendon divides into five slips for the 

 digits. That to the hallux receives the slender tendon from the M. 

 flexor digitorum longus. The other four slips provide the lumbrical 

 muscles, and are also joined by the tendons of the M. flexor 

 digitorum longus (tibialis). Each deep tendon is thus really 

 double, and the distinction is readily to be ascertained. Moreover 

 in the first and fifth digits, the tendon derived from the M. flexor 

 digitorum longus (tibialis) winds round that derived from the 

 M. flexor hallucis longus (fibularis) 1 . 



A review of these complicated arrangements or a comparison 

 with those in the human hand and foot respectively, leads to the 

 inference that the determining factor is probably the necessity for 

 providing a strong grasp. The same conclusion will be drawn 

 from the general form of the foot, particularly perhaps in regard to 

 the wide angle of separation of the hallux from the remaining digits. 

 The interosseous muscles are (as in the human hand) disposed 

 with reference to an axis passing through the median digit. 



On the whole, it appears that the musculature of the Lemur 

 differs from that of Man not so much in regard to the identity 

 of individual muscles, as in their disposition and attachments. 

 These differences are largely determined by the attitude habit- 

 ually adopted in each case. 



G. Vascular System. The heart 2 is conical, having transverse 

 and dorsi-ventral diameters of nearly equal length. In formalin- 

 hardened specimens the acute and obtuse margins are distinct. 

 Both ventricles extend to the apex of the heart. The long axis of 

 this organ is sharply inclined to the axis of the post-caval vein 



1 For variations in the Lemur and other Primates, the excellent paper by Sawa- 

 lischin in the Morpkologisches Jahrbuch, Band xlii. Heft 4, 1911, should be 

 consulted. 



2 Patten, Trans. Boy. Acad. Medicine in Ireland, Vol. xvn. 1899. 



