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Show 624 MR. P. CHALMERS MITCHELL ON THE [June 16, which is separate and muscular in Palamedea, separate and tendinous in Gcdlus. Temporalis.-The superficial portion of this muscle is very large and inseparable into layers; it arises from the whole temporal fossa, and from the external and internal surfaces of the mid-temporal process ; it runs forwards and downwards under the quadrato-maxillary bar to the outer upper surface of the lower jaw; internal to this, and arising from the deeper region of the temporal fossa, is a strongly marked pyramidal muscle, which ends in a stout tendon inserted to the inner surface of the lower jaw. A still deeper portion runs across from the forward process of the quadrate to the inner side of the ramus. Lastly, a wide band of muscle bridges the narrow interval between the inner edge of the forward process of the quadrate and the wall of the orbit behind the optic foramen. Pterygoid.-A superficial portion, similar to that found in Ducks and Geese runs from the ventral, posterior end of the lower jaw to the palatal membrane. It is not so tendinous as in the Ducks and Geese. The deeper portion of the pterygoid is an almost continuous mass of muscle, inseparable into regions, from the pterygopalatine area to the lower jawr. MUSCLES OF THE LEG. Variations in the Conditions of the Ambiens. In the musculature of the leg there are several points (illustrated by figure 3, p. 625, and figure 4, p. 626) to which I wish to refer. As Garrod showed, the four muscles which he called A, B, X , and Y, the femoro-caudal and its accessory, the semitendinosus and its accessory, are all present. The interconnections between the muscles at the back of the knee differ so in birds that a description of their exact condition in Opisthocomus may be placed on record, although I have not yet sufficient material to make comparisons of any value. The adductors have no insertion to the tibia, but send a strong slip to the middle head of the gastrocnemius. The semimembranosus, the most posterior of the thigh-muscles, runs straight in to the tibia, unconnected with the tendon of the semitendinosus. The accessory semitendinosus is very broad and strong, but does not nearly reach the tibia, being separated from that by the middle head of the gastrocnemius. The semitendinosus, after being joined by its accessory, sends in one fibrous slip to the tibia, proximal to that of the semimembranosus; while the greater mass of the muscle ends in a strong tendon, which runs down alongside and soon fuses with the middle head of the gastrocnemius, before that reaches the tibial head. The condition of the ambiens muscle is still more interesting. Garrod (see paper referred to above) examined the legs of three specimens of Opisthocomus. In all cases he found the ambiens small, but normal, above the thigh. In five of the six legs it was |