THE MYOLOGY OF THE ANTHROPOMORFHA. 409 



these is sometimes, and the latter frequently, wanting in the 

 human subject. 



The flexor accessoriiis appears to be regularly absent in 

 Sylohates and Plthecus^ and, in the majority of cases, in the 

 Chimpanzee. The transversus pedis seems to be absent in the 

 Orang, but it is present in the other Anthropomorpha. 



Many muscles which exist both in these Apes and in Man 

 have different orio^ins in the former. Thus, the solceus has 







only a fibular head, and takes no origin from the tibia. The 

 flexor brevis digitorum pedis never arises altogether from the 

 calcaneum, but a large proportion of its fibres spring from the 

 tendons of the deep flexors. The calcaneal head furnishes the 

 tendons for the second, or the second and third, digits. The 

 interosseous muscle which lies on the tibial side of the middle 

 digit of the pes, usually arises from the fibular side of the sec- 

 ond metatarsal as well as from the tibial side of its own meta- 

 tarsal, and its origin lies on the dorsal side of that of the fibu- 

 lar interosseous muscle of the second digit. Hence, of the so- 

 called dorsal interossei (or interossei which are visible on the 

 dorsal aspect of the pes) two belong to the middle digit, and 

 one, to the second and fourth digits respectively ; which is- 

 the same arrangement as that which obtains in the manus. 

 The flexor 2^ollicis is more or less closely connected with the 

 flexor cominimis perforans, or with that part of the muscle 

 which goes to the index digit. The connection is slightest in 

 Hylohates, the origins of the two muscles, only, being united. 

 It is most extensive in the Orang, in wliich no tendon goes to 

 the pollex. The same complete loss of the flexor pollicis^ as 

 a thumb-muscle, occasionally takes place in the Gorilla ; but 

 in this animal, as in the Chimpanzee, the rule appears to be, 

 that the flexor pollicis unites at its origin with part of the 

 flexor perforans^ and that the fleshy fibres converge to a com- 

 mon tendon which di\ddes into two, one for the pollex and 

 the other for the index. In Hylohates^ the short head of the 

 hiceps hrachli arises from the pectoralis tnajor^ and the ad- 

 ductor hcdlucis and trmisversus p)edis form but one muscle. 



The flexor longus hallucis takes an origin from the ex- 

 ternal condyle of the femur in the Orang ; and the peetorcdis 

 major arises by three distinct slips. 



Some of the muscles in the Anthropomorpha differ in 

 their insertion, or in the extent to which they are subdivided, 

 from what is usual in the corresponding muscles of Man. 

 Thus the extensor ossis metacarpi pollicis ends in two distinct 

 tendons • one for the trapezium, and the other for the base of 

 18 



