176 Proceedings of the Royal Physical Society, 



to make out the precise limits of its origin. A tendon was 

 developed which passed out of the pelvis over the lesser 

 sciatic notch, and was joined by the two gemelli. Plication 

 of the tendon was scarcely to be seen at all. It was inserted 

 into the depression on the inner side of the great trochanter, 

 in conjunction with a gemellus on either side, and the tendon 

 of obturator externus below. 



It was supplied on its perineal surface by a branch of the 

 great sciatic nerve, which joined the internal pudic, but left 

 that nerve again to be distributed to the muscle. This 

 branch was followed back to its origin from the 4th and 

 5th lumbar nerves. 



The gemelli muscles were both well developed, but the 

 inferior was by far the larger. 



The superior gemellus arose from the very poorly developed 

 ischial spine. The inferior arose from the ischial tuberosity 

 at the lower margin of the small sciatic notch. 



They were both inserted into the tendon of the obturator 

 internus, overlapping it, so that the two met and covered up 

 the tendon from view, and they were carried by it to the 

 great trochanter, into which they were also inserted. 



They were both supplied by a branch given off from the 

 great sciatic nerve to be distributed to them and to the 

 caudo-femoralis. This branch was traced back to the 4th 

 and 5th lumbar nerves. The inferior gemellus was also 

 supplied by the nerve to quadratus femoris. 



Fusion of the tendon of obturator internus with that of 

 obturator externus is also seen in Anthropoid apes (8). 



It is not a muscle given to much variation in monkeys 

 generally. 



The gemelli in the lemurs have the same attachments 

 and relations as in the Hapale, and the inferior is the 

 larger (2). In Cynocephalus anubis the inferior is the smaller 

 muscle. In Anthropoid apes the inferior is with difficulty 

 separated from the quadratus femoris (8), and in the chim- 

 panzee it is smaller than the superior (7). In Hylohates the 

 superior gemellus is not a separate muscle (8). 



Quadratus femoris was relatively a very large muscle, and 

 had an extensive origin from all the outer surface of the 



