Some veterinary anatomists have given to the inferior and external articular surface of the humerus the name of trochlea; and to the internal one, that of condyle. On this account they designate the external prominence as the epitrochlea, and the internal one as the epicondyle. In addition to the fact that this point of view is not legitimate, it produces inevitable confusion when comparing the parts with those of the human humerus, and this confusion exists, not alone in describing the bone, but also in the description of the muscular attachments, and in the comparison of the muscles of the forearm of quadrupeds with the corresponding muscles in the human species. The radius is placed in front of the ulna; its body, slightly convex forwards, has the anterior surface convex transversely, and the posterior surface plane in the same direction. It is to the external part of this latter that the ulna is applied, which is completely fused with the radius. The superior extremity of the radius is a little larger than the inferior. Its superior aspect, concavo-convex, moulded on the inferior articular surface of the humerus, presents internally two cavities, which receive the lips of the trochlea, and, externally, another, smaller, cavity, which receives the condyle. The radius articulates with the trochlea and the condyle, having appropriated a portion of the ulna, as is proved by the presence of the coronoid process, which belongs to the former. This superior extremity presents, internally, a tuberosity into which the biceps is inserted; this is the bicipital tuberosity; and on the other side is another tuberosity, which is a little more prominent than the preceding. The inferior extremity, which is flattened from before backwards, is furrowed on its anterior surface by grooves for the passage of muscles (the names of the muscles whose tendons pass in these grooves have already been given on p. 43). It articulates at the lower end with the superior row of the carpus, and it terminates laterally in tuberosities: one, external, on which is found a groove for the tendon of the lateral extensor of the phalanges, the homologue of the special extensor of the little finger; the other, internal, is a little more prominent than the one we have just described. These tuberosities are visible under the skin which covers the superior and lateral parts of the region known as the _knee_; but which, we again repeat, is no other than the wrist.