BUCEROTES -217 



The biceps is occasionally (e.g. B. el at us) double at its 

 origin, the tendons being separated by quite a quarter of an 

 inch. 



The arrangement of the semitendinosus and adductor in 

 Aceros nipalensis, which is somewhat complex, will be 

 understood from the accompanying drawing (fig. 101). 



The semitendinosus (St) is inserted on to the tibia by a 

 long, thin, flat tendon ; another tendon, joining the first just 

 where it passes into the muscle, is attached to the gastro- 

 cnemius. 



The accessory semitendinosus is in two parts : the larger 

 half (Ast) is attached to the semitendinosus just behind the 

 origin of the tendon of insertion of the latter ; the second 

 half appears to arise from the tendon which connects the 

 semitendinosus with the gastrocnemius, it passes up towards 

 the thigh, and just in front of its (tendinous) insertion on to 

 the femur it receives a tendon from the adductor. This 

 latter muscle (the adductor longus) is inserted by three 

 tendons (1) to the femur; (2) a small tendon which has 

 already been described as joining the second half of the 

 accessory tendinosus ; and (3) near to the origin of one of 

 the internal heads of the gastrocnemius ; to this tendon is 

 also attached the inner head of the gastrocnemius. 



The corresponding muscles l of Bucoruiis abyssinicus are 

 rather simpler than in Aceros nipalensis. The adductor 

 longus is only inserted at two places : first, by a fleshy inser- 

 tion along a considerable length of the lower border of the 

 femur ; second, by a tendon in common with the inner- 

 most head of the gastrocnemius. The semitendinosus is 

 attached by a thin tendon to the tibia, as in Aceros, and by a 

 short tendon, also as in that species, to the gastrocnemius. 

 The accessory semitendinosus arises chiefly from this latter 

 tendon, but there is no division between this part of the 

 muscle and that which takes its origin from the fleshy part 

 of the semitendinosus. 



In Buceros atratus there is, again, some little difference 



1 GADOW figures most of these muscles in Bronn's TJiicrrcich, ' Aves,' J'xl. 

 vi. Abth. iv. Taf. xxiii. b, fig. 1. 



