Cuvier thus defines the supracondyloid canal in the Lion:—"Audessus du condyle interne, la ligne âpre est aussi percée d'un trou pour le passage de l'artère cubitale"[1]. But this is not the homologue of the commonly called "supracondyloid canal" in the humerus of certain Reptilia. The "internal condyle" of Cuvier and anthropotomy is the "ulnar condyle;" the "external condyle" is that which is termed "radial" in vertebrate anatomy. Thus the zootomist has to take into account, in the application of his science to Palæontology, of an "ulnar supracondyloid foramen," and a "radial supracondyloid foramen." There is, also, a third perforation of the distal end of the humerus distinct from both, which may be termed an "inter-condyloid foramen." It is that which is present in the humerus of the wolf[2] and some other mammals, but of which I have not found any example in recent or extinct Reptilia. While upon this comparison I am tempted further to remark that, in comparative anatomy, zootomy, or anatomy properly so called, the term "condyle" is restricted to portions of bone more or less convex, modified for the articulation of two bones, and usually covered with synovial cartilage. Anthropotomy, however, in reference to such portions of the distal articular surface of the human humerus, calls the radial condyle the "radial head," and the ulnar condyle the "ulnar trochlea," and restricts the term "condyle" to the tuberosities which project beyond and somewhat above the articular prominences, which, in the humerus, answer to the corresponding prominences rightly termed "condyles" in the femur[3]. I have found it useful, in comparisons of the humerus akin to those in the present paper, to call the anthropotomical condyles "epicondyles," as being parts projecting somewhat above, or proximad of, the true condyles, and to distinguish them as "entepicondyle " and " ectepi- condyle" respectively. Thus the canal which gives passage to an artery and commonly a nerve at the distal end of the humerus in Felines, and most Marsupials, is an entepicondylar canal or foramen; and this it is which characterizes the humerus of Cynodraco. The canal which gives passage to a blood-vessel in the humerus of certain Chelonia and Lacertilia is an ectepicondylar canal; and its presence in no way affects the resemblance (I will not say affinity) to the feline Mammalia which the extinct Cynodraco presents in its humerus as in its dentition.
I am of opinion, though it is difficult to judge from the woodcuts of small and fragmentary humeri ascribed to Dicynodon by Prof. Huxley in the 'Memoirs of the Geological Survey of India,' that the "supracondyloid foramen" there indicated at a, figs A and B, p. 10, is not the homologue of the "supracondyloid foramen" which "occurs not unfrequently among Lacertian Reptiles," but that it differs not only in "form and proportions," but likewise in relative position, and that in Dicynodon it concurs with the pair of
