MAY, 1921. AMERICAN MARSUPIAL, CENOLESTES OSGOOD. 37 



Glutens minimus. Origin from the dorsal surface of the ilium from a 

 point on the acetabular border about midway between the crest and the 

 acetabulum to a point opposite the middle of the acetabulum. Insertion 

 broadly covering the antero-internal surface of the great trochanter of 

 the femur. It is relatively large and completely distinct not only 

 anteriorly from the glutens maximus and glutens minimus but posteriorly 

 from the gemelli. In the didelphids and various other marsupials it is 

 partially joined to the maximus. 



Pyriformis. Origin fleshy from the dorso-lateral surface and the 

 caudal edge of the crest of the ilium and from the tips of the transverse 

 processes of the two sacral and the first caudal vertebrae. 



Insertion on the apex of the great trochanter of the femur just caudad 

 of the insertion of the glutens minimus and en tad of the glutens medius. 

 A very large muscle lying entad of the glutens medius and ecto-caudad of 

 the glutens minimus. Its anterior border which is full and rounded runs 

 direct from the trochanter to the iliac crest and at least in its distal half 

 is tendinous. Fleshy fibers pass dorsad from this broad tendinous edge 

 to the sacral border. Its outer surface, at least caudally, is somewhat 

 connected with the glutens medius. 



Quadratus femoris. Origin on the inner side and slightly ventrad of 

 the tuberosity of the ischium and on the inner edge of the ischium just 

 craniad of the tuberosity. The fibers curve over the lesser sciatic notch 

 to pass outward to their insertion on the middle of the ventral edge 

 of the great trochanter of the femur and on the intertrochanteric ridge. 

 It is relatively large and well developed and fairly distinguishable from 

 the gemelli anteriorly. 



Gemelli. No distinction is evident between a gemellus superior and 

 inferior. The origin is on the body of the ischium dorsad of the origin 

 of the ischiococcygeus. The insertion is with the tendon of the obturator 

 internus on the caudal edge of the great trochanter of the femur and in 

 the digital fossa proximad of the insertion of the quadratus femoris. Its 

 cranial border is distinct from the caudal border of the glutens minimus. 



Iliacus. Origin from the ventro-lateral or iliac surface and the 

 acetabular border of the cranial two-thirds of the ilium from the crest 

 caudad. In its caudal portions its insertion is opposite that of the 

 iliococcygeus on one side and the glutens minimus on the other with a 

 part of the psoas magnus lying loosely between. Its general relations are 

 closely similar to those in Didelphis. 



Obturator internus. Origin from all of the caudal border of the ramus 

 of the ischium which is ventrad of the quadratus femoris, from the inner 

 side of the pubic symphysis, and from the caudal border of the obturator 

 foramen. Insertion by a flat tendon in the digital fossa of the femur. 



