PUYSIOLOGY, AND PATHOLOGY OF THE CHIMPANZEE. o57 



tendons of gluteus medius from those of the scansorius and 

 pyriformis. It is the largest of the glutei. The whole insertion 

 is by closel3''-set ribbon-like muscles. ]S"one of these forms a 

 separated part as described by Champneys (11), but the insertion 

 is split slightly by the vastus externus, as described by 

 Hepburn (24). 



The scansorius arises from the body of the ilium by a thick 

 muscular origin, and by a thin curved origin from the ilium an 

 inch behind a.nd parallel to the acetabulum. The most external 

 fibres come into relation with the gluteus minimus. It passes 

 over the acetabulum and head of the femur to be inserted into 

 the capsule of the hip from the head to the top of the great 

 trochanter, and to the anterior border of the great trochanter 

 internal to the pyriformis, gluteus medius and vastus externus. 

 It is continiious above with the obturator internus and the 

 gemelli, and below with the gluteus minimus. 



The gluteus ininimus arises from the anterior border of the 

 ilium from the anterior superior spine to below the anterior 

 inferior spine. It is on a slightly more anterior plane than the 

 scansorius. Its insertion is linear and continues that of scansorius 

 downwards for a centimetre. The insertion is covered by the 

 vastus extei'nus. 



The tensor fasdce femoris arises from the back of the iliacus, 

 and is inserted into the fascia of the leg more ' than half-way 

 down the leg. Some authors have stated that the scansorius 

 corresponds to the tensor fascise, and others describe only the 

 former. Ohampneys (11) describes both. 



The gemellus superior (text-fig. 36, Gem. Sup) ai-ises from a 

 small area on the outer surface of the ischial spine, and from the 

 attachment of the lesser sacro-spinous ligament above the groove 

 for the tendon of the obturator internus. The gemellus inferior 

 (text-fig. 36, Gem.Inp) arises within the pelvis from a linear 

 oi'igin, and from the top of the outer aspect of the tuber ischii 

 below the groove for the tendon of the obturator internus. The 

 tendon of the obturator internus (text -fig. 36, Obt.Int) formed by 

 a fusion of fascicles, is separated from its groove in the ischium 

 by a bursa. It is overlapped by the gemelli which fuse over it. 

 They all have a common insertion into the femur above the 

 trochanteric pit. It is intimately connected to the capsule 

 of the hip joint. Between the hip joint and the tendons of 

 obturator internus and gemelli and the quadratus femoris and 

 obturator externus there is a pad of fat. Hepburn (24) states 

 that the gemellus superior is less than the inferior, and it is 

 difficult to separate the latter from the quadratus femoris, but 

 that is not the case in this animal. Champneys (11) agrees with 

 me in the relative sizes of the gemelli. 



The quadratus femoris arises from the inferior ramus and 

 upper edge of the tuber ischii above the origin of the hamstrings. 

 It has an angular insertion into the lower part of the inter- 

 trochanteric crest and lesser trochanter, and then horizontally 

 Proc. Zool. Soc— 1923, No. XXIV. 24 



