MUSCULAR SYSTEM OF THE RED HOWLING MONKEY 139 



Bodini (1965) has found in the spider and woolly monkeys a clear 

 origin of the muscle from the acetabular margin. The insertion in 

 both animals is on the trochanter major according to Bodini (1965), 

 but Hill (1962) attributes such termination only to Ateles. He says 

 that in Lagothrix the gluteus maximus ends on the fascia lata. Klaatsch 

 (1900) regards the muscle as stronger in Alouatta than in either 

 Ateles or Lagothrix. The gluteus maximus of Cebus appears to be 

 larger than in any of the other four prehensile-tailed cebids and 

 always associated with a large caudofemoralis which, nevertheless, 

 is not well separated from the large gluteus (Bodini, 1965). M. gluteus 

 medius is large in Ateles, as could be expected from the broadened 

 iliac blade of the animal. Waterman (1929) attributes this osteological 

 character to the attachment on the pelvis of some muscles related to 

 the brachiating habits of this genus. Its piriformis is intimately 

 associated with the mesogluteus (Bodini, 1965; Hill, 1962). Roberta 

 Bodini (personal communication) has informed me that this muscle, 

 which she regards as just a part of the gluteus medius, is small in 

 Ateles when compared to Cehus. To her this indicates that the rotating 

 and abducting possibilities of the piriformis are reduced in the spider 

 monkey. This situation is in general comparable to my findings in 

 the howler where a small piriformis is closely associated to the larger 

 gluteus medius. I was, nevertheless, able to identify and separate 

 clearly the bellies of the two muscles. Their organization in Brachy teles 

 (Hill, 1962) and Lagothrix (Bodini, 1965; Hill, 1962) practically 

 duplicates the characters of the spider and howling monkey. The 

 resemblance of Brachyteles to Alouatta is striking. Hill (1962) reports 

 a cleavage plane through the medial gluteus very much like the one 

 I described in the muscle of the howler. Bodini (1965) did not find a 

 scansorius in Ateles and informs me that its gluteus minimus is very 

 much reduced, otherwise these two muscles in Lagothrix (Bodini, 

 1965; Hill, 1962) and Brachyteles (Hill, 1962) resemble those of the 

 howler. In Cehus the gluteus medius, pars piriformis, is strongly 

 developed, contrasting with the pattern in the other four genera 

 but resembling Saimiri; its gluteus minimus and scansorius have 

 their origins occupying the entire supracetabular portion of the 

 gluteal plane (Bodini, 1965). 



Cruropedal Group 



LATERAL DIVISION 



M. peroneus longus: This long muscle covers the short peroneus 

 and arises from (fig. 38) the lateral surface of the head and upper 

 fifth of the fibular shaft, the peroneal portion of the crural aponeurosis 

 and the fascia between the two peroneal muscles. Its fibers form a 

 longitudinal belly (fig. 44), passing distally to the proximity of the 



275-199 O - 68 - 10 



