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Show 590 MR. F. E. BEDDARD ON THE [Dec. 3, Buceros lunatus and B. bicornis, which are both large species, hardly present any differences from B. rhinoceros. Bycanistes sub cylindric us has a syrinx which, although of about the same size as that of Ceratogymna elata, shows certain differences which are worth putting on record. In the first place, the syrinx is much compressed from side to side at the level of the last tracheal ring; in the second place, the last tracheal ring is very much more arched than usual; it forms indeed almost a complete semicircle. The intrinsic muscle of the syrinx in this, as in the other smaller Hornbills, is very much larger relatively than in the larger species. Anthraceros malayanus, again, is a little different from all the types hitherto described. The last tracheal rings are but little fused posteriorly, only the penultimate and antepenultimate rings are so fused, so that it is impossible to be certain as to the origin of the pessulus. The intrinsic muscles are slender. Toccus presents certain peculiarities which I have not yet observed in any other Hornbills; tbe trachea has two pairs of extrinsic muscles given off about | an inch apart. This condition seems to me to be so remarkable that I have preserved the specimen which shows it, though unfortunately the insertions of the anterior pair of muscles are lost and I have no recollection of where the point of insertion was. The intrinsic muscles are relatively small. There appears to be no fusion between any of the tracheal rings. Myology. Tbe arrangement of the semitendinosus and adductor in Aceros nipalensis, which is somewhat complex, will be understood from the accompanying drawing (woodcut, fig. 3, p. 591). 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 gastrocnemius. 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 muscles1 of Bucorvus abyssinicus are rather simpler than in Aceros nipalensis. The adductor longus is only inserted at two places : first by a fleshy insertion along a considerable length of the lower border of the femur; second by a tendon in 1 Gadow figures most of these muscles in Bronn's ' Tbierreichs,' Aves, Bd. vi. Abth. iv. Taf. xxiii. b. fig. 1. |
