OF DIDELPHYS VIRGINIANA. 



125 



around the border of the ischium, just in front of the ischio-coccygeus, and, receiving the 

 gemelli, proceeds to be inserted into the digital fossa. 



Gemelli — The accessory muscles of the foregoing are well developed, lying along either 

 border of the tendon, distinct from each other above, blended together below. They arise 

 from the edge of the ischium, and are inserted into the tendon near the insertion of the 

 latter. 



Ilio-femoraUs. — {Scansorius Traill.) Besides the preceding six little muscles about the 

 hip joint, there is another and very curious one. It is a small, very slender fasciculus, aris- 

 ing from the upper border of the acetabulum alongside the origin of the rectus, running 

 straight down over the 

 front of the joint, and 

 there curving a little in- 

 ward to gain, and be in- 

 serted into, the base of 

 the trochanter minor. It 

 thus lies in precisely the 

 position of that anterior 

 longitudinal ridge, pro- 

 duced by thickening of 

 the capsular ligament, 

 known in human anatomy 

 as the '' ligamentum ilio- 

 femorale." In the pre- 

 sent instance this liga- 

 mentous ridge does not 

 exist. It is undoubtedly 

 the same muscle as that 

 described by Traill in the 

 ape, under the name of 

 Sca7isorius. 



Fig. 32. — Muscles of the left leg, outside — about four-fifths natural size. 



There are four flexors of the thigh and extensors of the leg— the sartorius, rectus, and 

 twovasti; and, likewise, four proper extensors of the thigh and flexors of the leg — the 

 gracilis, semitendinosus, semimembranosus and biceps. To the latter, however, must be 

 added the femoro-coccygeus, when fully developed ; and also the muscle below described 

 as the cruro-coccygeus. The last named divides into two distinct slips, with opposite inser- 

 tions in the leg ; so that there are really seven leg-flexing tendons that come down along 

 the back of the thigh. The remarkable disposition of these is shown in the accompanying 

 figures. Great flexing power is insured by their low insertions ; and rotation of the knee 

 is subserved by their peculiar relation to each other. There are three adductors, which, 

 however, act chiefly as extensors, and a pectineus, which is really an adductor. The con- 

 tour and disposition of all the muscles is such that the thigh is very thin from side to side, 

 and very deep antero-posteriorly. The bulk of muscle upon the back of the thigh pre- 

 ponderates over that upon the front almost as much as the calf-muscles do over those of 

 the anterior region of the leg. 



Sartorius.— {Fig. 32, a, and fig. 31, d.) A rather slim, flattened ribbon stretched be- 



HKM:0IRS B08T. 80C. HAT. HIBT. VOL. II. 



82 



