OCR Text |
Show 1873.] CERTAIN MUSCLES OF BIRDS. 637 ternus of these birds, which is perplexing at first sight. In Sula this muscle, instead of, as usual, being inserted into the outside of the head of the femur, has its attachment further forward, to the outer edge of the linea aspera, or the bony surface corresponding to it, midway between the head of the bone and the attachment of the femoro-caudal muscle. In Phalacrocorax it is situated still further forward, being in contact by its anterior border with the posterior margin of the femoro-caudal, parallel to it in direction, and otherwise in situation exactly like an accessory femoro-caudal. However, that it is the obturator externus and not the accessory femoro-caudal is certain, from the facts that the nerve to the semimembranosus is superficial to it, that the whole upper part of its outer surface is covered with a tendinous layer, that none of its anterior fibres blend with the posterior margin of the upper end of the tendon of the femoro-caudal, and that the presence of this muscle is constant in birds. The accessory femoro-caudal is, on the contrary, superficial to the nerve to the semimembranosus ; it is not tendinous externally up to its insertion ; some of its fibres blend with the tendon of the femoro-caudal just before it joins the femur ; and its presence is uncertain. In Sula the ambiens has a tendinous link at the outer side of the knee, which runs upwards from it to the outer side of the anterior fibrous expansion over the joint. Species examined. Sula bassana. Phalacrocorax lugubris. Phalacrocorax carbo. The Ardeidae possess the femoro-caudal, though in some, as Ardea goliath, it is extremely narrow, the semitendinosus, the accessory semitendinosus, and the postacetabular portion of the tensor fasciae which is very slightly developed; the ambiens and the accessory femoro-caudal are absent. Species examined. Ardea cinerea. Ardea egretta. goliath. garzetta. purpurea. Nycticorax europceus. alba. Botaurus stellaris. The Ciconiidae possess the ambiens, the semitendinosus, and the accessory semitendinosus ; the accessory femoro-caudal is absent. The femoro-caudal is very small in Ciconia and absent in Leptoptilus; and the postacetabular portion of the tensor fasciae is the same. Species examined. Ciconia alba. Ciconia maguari. , nigra. Leptoptilus crumeniferus. The Plataleidae possess the ambiens, the femoro-caudal, the accessorv femoro-caudal, the semitendinosus, the accessory semitendinosus," and the postacetabular portion of the tensor fasciae, which is small. |