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U.S. NATIONAL MUSEUM BULLETIN 2 73 



explains that the relations of the muscle in Brachyteles are the same 

 as in Ateles, but its transverse dimensions are more reduced. The two 

 woolly monkeys have a bicipital rectus femoris and three well- 

 differentiated vasti (Hill, 1962). Ateles is not so thorough in the 

 independence of its vasti (Hill, 1962). Cebus (Hill, 1960) has not a 

 bicipital femoral rectus, but in other respects the resemblance to 

 Alouatta, Brachyteles, and Lagothrix is strong. 



Figure 41. — Muscles of the gluteal region (1, fibers of m. gluteus medius arising from the 

 dorsally facing portion of the gluteal plane; 2, m. scansorius; 3, termirial portion of m. 

 gluteus maximus; 4, m. quadratus femoris; 5, mm. gemelli and m. obturatorius internus; 

 6, m. ischiocaudalis; 7, m. piriformis, sectioned; 8, fibers of m. gluteus medius arising 

 from the laterally facing part of the gluteal plane). 



