primrose; the anatomy of the orang outang 
51 
the anterior margin of the ilium at a point 3 cm. below the anterior 
superior spine, the width of origin being 2 cm., lying behind the iliacus 
and in front of the gluteus minimus; it passed into the thigh to join the 
quadriceps extensor muscle in the usual way. There was no reflected 
head of origin. Hepburn^ found the double origin in the Orang, 
Chimpanzee and Gorilla, but not in the Gibbon. In establishing 
homologies between the muscles of the thigh and of the arm Hum- 
phrey^ considered the rectus in the thigh to represent the scapular part 
of the triceps in the arm ; and the shorter deeper portion, extending more 
laterally, formed by the vasti and crureus in the thigh, as representing 
the humeral head of the triceps in the arm. 
The Vastus externus (Plate VI, fig. 8, v.i.) arose from the anterior 
inter-trochanteric line and from a line skirting the lower part of the 
great trochanter. Posteriorly a part arose from the trochanter itself 
This part of the origin of the vastus externus embraces the insertion of 
the scansorius. Below this point the vastus externus arose from the 
postero-external aspect of the femur as low as the condyle, its origin 
here being immediately in front of the insertion of the gluteus maximus. 
The Vastus internus arose from the antero-internal aspect of the 
femur as high as the root of the neck, its origin extending down to the 
internal condyle. 
The Crureus arose from the anterior aspect of the femur as high 
as the neck, extending down between the lines of origin of the 
external and internal vasti as in man. These various muscles united as 
in man to form quadriceps extensor cruris. This muscle is developed 
in apes as in man. 
The Gluteus maximus (Plate VI., fig. 8, g. max.) arose from the pos- 
terior part of the iliac crest, the back of the sacrum, coccyx, and the 
sacrosciatic fascia by an origin 6 cm. wide, and was inserted, the lower 
(posterior) fibres, by a rounded cord which was traced down the 
external aspect of the femur to the external condyle, being intimately 
attached to the fascia lata throughout its whole extent. Most of the 
superficial fibres converged to this rounded tendon and have thus a 
fascial insertion, whilst the deep fibres were inserted into the femur by 
an attachment 1.5 cm. wide immediately external to the vastus 
externus, behind that muscle; the biceps lying posteriorly. The gluteus 
maximus was thus a very well developed muscle, and the proverbial 
1 Loc. cit., p. 329. 
2 Humphrey, “ On the Disposition and Homologies of the Extensor and Flexor Muscles of the 
Leg and Forearm.” Journ. of Anatomy and Physiology, Vol. HI, 1869, p. 320. 
