MUSCULATURE. 277 



What is clearly the gluteus medius (Plate 1, fig. 1, gme) is present in much 

 the usual relations. It is a large muscle-mass arising from the lateral face of 

 the Uium, and from fascia connecting the spines of the last lumbar and first 

 two sacral vertebrae. It inserts on the head of the femur from the gi-eat tro- 

 chanter to the acetabulum. What seems also to be a division of this muscle 

 arises from the lateral part of the tuberosity of the ilium and passes as a rather 

 easily separable bundle to an insertion about 10 mm. long at the proximal 

 end of the trochanteric ridge. The muscle here considered the gluteus medius, 

 Mivart and Westling have taken to be the minimus, since they assigned to the 

 medius the crural division of the maximus. The minimus is, however, wanting 

 as a distinct muscle in both the Echidna and the Proechidna. 



The pyriformis (Plate 1, fig. 1, py) seems to be represented by a small muscle 

 from the tips of the transverse processes of the fourth sacral and first caudal 

 vertebrae. It passes over the posterior tuberosity of the femoral head and 

 inserts on the lateral side of the trochanteric ridge at slightly less than half 

 its length, just caudal to the insertion of the gluteus maximus. Between the 

 latter and the pyriformis issues the sciatic nerve. Mivart found a similar 

 muscle in the Echidna arising from five caudal vertebrae, but Westling failed 

 to find it. Mivart notes that the nerve is superficial to the muscle instead 

 of beneath it as usually. 



The capsularis shows the usual relations. It arises as a thin sheet from the 

 ilium between the acetabulum and the origin of rectus femoris and spreads out to 

 an insertion about 10 mm. long at the proximal portion of the trochanteric ridge. 



The quadratus femoris is a large muscle from a triangular origin extending 

 from the tuberosity of the ischium to the acetabulum. It is inserted by tendi- 

 nous fibers on the great trochanter just distal to the insertion of the gluteus 

 medius and for about 10 nun. along the trochanteric ridge. Mivart speaks 

 of this as a "delicate" muscle in the Echidna. 



The obturator externus appears to be much as in the Echidna. It is large, 

 of a triangular outline, and lies as usual underneath the adductor femoris. It 

 originates from the anterior edge of the pubis at the base of the epipubic bones, 

 and thence along the entire pubic symphysis and for about 15 mm. on the ramus 

 of the ischium. At the most anterior portion the origin extends from the pubic 

 border to the Up of the obturator foramen, but elsewhere it is from the outer 

 edge of the pubis and ischium, whence it tapers slightly to the insertion in the 

 entire intertrochanteric fossa. 



The obturator inter nus is wanting as in the Echidna. 



