OCR Text |
Show 1873.] ANATOMY OF STEATORNIS. 533 attached to the middle of the first fully developed half ring. The depressor muscles of the trachea are independent of these. Steatornis has two carotid arteries, as have both the Strigidae and Caprimulgidae. With regard to the myology of this bird, the only muscles which will be considered are those which have been found to have some bearing on the systematic position of birds generally. In the thigh, the ambiens (Sundevall)-the slender muscle which in many "birds runs from the innominate bone, just above the acetabulum, along the inner side of the thigh to the knee, which it crosses obliquely in the fibrous capsule below the patella, and then blends with the flexor perforatus digitorum-is absent, as it is in the Strigidae and Caprimulgidae. The semitendinosus, the outer of the two muscles which form the lower fold of the thigh (the semimembranosus being the inner), and which runs from the region of the lower end of the innominate bone to the tibia, is present, as in the Caprimulgidae, it being quite absent in all the Strigidae. As in the Caprimulgidae also, this muscle Muscles at the outer side of the elbow : A, of right wing of Caprimulgus europceus; B, of left wing of Steatornis. tp b, tensor patagii brevis; ecr, extensor carpi radialis; b, biceps; d, deltoid ; t, triceps; h, humerus. receives an accessory head from the lower end of the femur, which helps to send a partial insertion of the muscle down the leg. The femoro-caudal (which runs as a narrow muscular ribbon from the middle of the linea aspera of the femur to the coccyx, covered by the semitendinosus and crossed superficially by the sciatic artery and nerve) is quite absent; it is well developed in the Caprimulgidae, small in the Strigidae, and absent in very few birds. In the upper limb the second pectoral (subclavius of Rolleston) is not large, extending about halfway down the sternum, as it does |