168 THE MYOLOGY OF THE EAVEN. 



whorl-like, overarching portion of the ilium behind ; 

 and finally from the contiguous portion of the pelvis 

 over the antitrochanter, between these anterior and 

 posterior origins. In front the muscle consists first of a 

 strong layer of semitendinous fascia, which closely over- 

 lies the glutens medius muscle beneath it, and overlaps 

 the sartorius anteriorly. The posterior origin and mid- 

 division become rapidly carneous and more massive as 

 we proceed in the direction of the caudal extremity of 

 the body. So that, where we find it arising from be- 

 neath the overarching part of the ilium behind, the 

 muscle fills about one-fourth of the convexity there 

 formed, the semitendinosus filling the remainder of this 

 curious cavity. The fibres of the strong, semitendinous, 

 muscular sheet springing from these several origins, or 

 rather along this continuous line of origin, now pass, 

 converging as they do so, towards the anterior aspect 

 of the knee-joint. The semitendinous portion anteriorly 

 becomes fleshy as it arrives along the outer pelvic mar- 

 gin, with which it is quite intimately connected. The 

 hinder division of the muscle remains thick and car- 

 neous until it comes to the knee-joint. Here all the 

 fibres again become tendinous and fascia-like, and, 

 uniting with a similar structure contributed by the 

 extensor femoris lying beneath it, the combined sheath 

 thus formed surrounding the well-developed patella, 

 closely invests the front and sides of the knee-joint, and 

 is finally inserted all round the anterior and externo- 

 lateral borders of the summit of the tibia. 



" The glutens medius muscle (Fig. 63 bis] is found to 

 be strong and tendinous. It, as in all of the birds that 

 I have examined, fills the concavity of the pre-acetabular 

 portion of the pelvis, and here in Geococcyx extends 

 laterally much beyond the bone, as this bird has a very 



