186/.] MYOLOGY OF IGUANA TUBERCULATA. 791 



by the spine of the pubis, to the ischiatic symphysis. It is inserted 

 into the summit of tlie trochanter below, and superficial to, the other 

 two portions (fig. 17, Pc. 1). 



(2) The second part (fig. 17, Pc. 2) arises from the down-turned 

 lip of the pubis, from the acetabulum to the symphysis. It is in- 

 serted immediately beneath the preceding portion. 



(3) The third part (fig. 17, Pc. 3) arises from the symphysis 

 pubis, backwards to the middle of the obturator foramen. At the 

 posterior end of its origin the obturator externus is superficial to it 

 and overlaps it. It is inserted into the summit of the trochanter 

 immediately behind the second part. 



The adductor magnus (figs. 14 & 17, A.) is a rather large muscle, 

 which arises, by strong tendinous fibres, from the anterior part of 

 the strong tendinous arch before mentioned which ends in front at 

 the pubic spine. It is inserted into the inner side of the shaft of 

 the femur (for about the second and third fifths of its vertical ex- 

 tent) between the vastus externus and the vastus internus. 



Rectus /emor is (figs. 13, 14, 16 & \7,R.F.). This muscle arises, 

 by a very strong and rather broad tendon, from the ventral side of 

 the acetabulum. It blends with the other extensors of the leg and 

 with the a|)oneurosis of insertion of the gluteus maximus. 



Vastus internus. A rather small muscle (figs. 14 & 17, V. I.) 

 arising from the inside of the shaft of the femur, about as high as the 

 bottom of the uppermost third of the insertion of the adductor; 

 below it blends with the crureus and other extensors of the leg. 



Vastus externus (fig. 15, V. Ex.). This is exceedingly small, and 

 so intimately connected with the crureus as scarcely to admit of de- 

 finition. It arises from the lowest two-fifths of the postero-external 

 surface of the shaft of the femur, and is inserted with the rest of the 

 extensor mass. 



Crureus (figs. 16 & 17, C). This muscle is so intimately con- 

 nected with the last as to be separable from it only with great diffi- 

 culty. It arises from the front of the femur, its origin extending 

 up near to the head of the bone. It is inserted into the patella 

 along with the rest of the extensor muscular mass. At its summit 

 it is, in part, continuous with the fourth portion of the iliacus. 



Gluteus inaximus {1) . A muscular layer, which may perhaps re- 

 present the gluteus maximus of mammals*, arises by a very strong 

 tendinous fascia from the outer side and upper margin of the ilium. 

 It covers the antero-external side of the thigh, becomes intimately 

 united with the rectus femoris, and is inserted by aponeurosis into 

 the outer surface of the vastus externus (figs. 13, 14, 15 & 16, 

 G.Mx.). 



The gluteus medius arises from the outer surface of the ilium, be- 

 tween the origins of the gluteus maximus and ilio-peroneal. It is a 

 small muscle, and is inserted into the outer side of the upper part 



* I am very doubtful as to whetlier this muscle and the next are r^aWj glut ei ; 

 but the condition of these muscles in Echidna inclines me to name them so, pro- 

 visionally at least (see Trans. Linn. Soc. vol. xxv. ISHO, p. 391, and pi. .^3.3. fig. 2. 

 iG.nuv. and G.md.). 



