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Show 1903.] THE MUSCLES OF THE UNGULATA. 269 rises outside. Our reasons for coming to this conclusion are, firstly, that in dissecting away the obturator externus to expose, as we thought, the obturator tertius we found that the two muscles were practically one, and that no division was possible between them ; secondly, that the obturator membrane can be clearly seen on the pelvic surface of the so-called obturator tertius; and, thirdly, that the part of the muscle which passes through the obturator foramen is supplied by the obturator nerve, and not by a branch from the sacral plexus. This last fact is perhaps the one on which we are inclined to lay most stress. W e regret that in many of the animals which passed through our hands we did not pay enough attention to this muscle, and it was only when Text-fig. 25. Hip-region of Sheep, showing double Quadratus femoris muscle. G . M E D . Gluteus medius. O.I. Obturator internus. G.MIN. Gluteus minimus. O.E. Obturator externus. working through Hyrax with the aid of Mivart and Murie's paper that we first noticed it. W e have seen enough, however, to feel sure that it is present in the Suidse, Tragulidse, Giraffidaj, Bovidae, and Procaviidse. W e expect, from what we know of other muscles, that it will also be found in the Hippopotamicla?, Cameliclas, and Cervidae, if carefully and specially looked for, but the various writers on these families were, like ourselves, evidently ignorant of its existence. With regard to the Perissodactyla, we have satisfied ourselves, through the kindness of the authorities at the Royal Veterinary College, that no muscle passes through the |