I9 o S ] ANATOMY OF PHAL/ENOPTILUS, RIDGWAY. 233 



4. M. caud-ilio-flexorius (Caud. il. fix., PI. VI, Figs. 31, 32, 

 33> 34> 35)- Behind the last mentioned muscle this superficial 

 one is found. It is a small band-shaped muscle, coming from the 

 posterior border of the ischium. It is partially covered on its 

 anterior margin by the m. ilio-tibialis and m. ilio-fibularis. The ter- 

 mination is very peculiar. Coming from the under, distal surface 

 of the femur is a short, broad muscle, which fuses with the large 

 muscle mass, the line of fusion being almost at right angles to the 

 fibers of that portion. From its tibial side comes off a short mus- 

 cle bundle with fibers directed downward and the tendon of which 

 fuses with that of one of the leg muscles. This shows great devia- 

 tion from Gadow's (/. c.) description. 



5. M. ischio-flexorius (Isc. fix., PI. VI, Figs. 31, 33, 34, 

 35). This narrow muscle band comes from the distal border of 

 the ischium at its union with the pubis. It is covered anteriorly 

 by the last mentioned layer. Its thin, flat tendon finds insertion 

 on the anterior borders of the tibial neck. 



6. M. ilio-fibularis {II. fib., PI. VI, Figs. 31, 34, 35). This 

 layer becomes visible after the removal of the m. tibialis anterior 

 and posterior. It springs from the acetabular ilium. It ends in a 

 small, round tendon, which, passing through a tendonous loop at 

 the knee, continues down the leg to become inserted between fibula 

 and tibia at the point where the former becomes free from the 

 latter. 



7. M. femori-tibialis (Fm. tib., PI. VI, Figs. 33, 34, 35). 

 This is the largest of the thigh muscles. It is partially covered on 

 the ventral anterior border by the m. ilio-tibialis internus, dorsally 

 by the m. ilio-tibialis anterior. Its origin begins at the trochanter 

 and it is attached fieshily to the femur on both dorsal and ventral 

 surfaces. It finds a tendinous insertion at the knee joint, being at- 

 tached to the proximal border of the tibia. The separation into 

 parts as given by Gadow (/. c. ) can not be made out. 



8. M. caud. -ilio-femoralis (Caud. il. fm., PI. VI, Fig. 35). 

 This is revealed by the removal of the m. ilio-fibularis and m. caud- 

 ilio-flexorius. Its width where it passes under the m. caud-ilio- 

 flexorius is equal to that of the above muscle. It comes as a small 

 rounded tendon from the ventral lateral border of the pygostyle. 

 Just before reaching the ischium the tendon passes over into the fleshy 

 muscle. This bends around in a semicircular fashion to the proximal 



