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Show 1867.] MYOLOGY OF IGUANA TUBERCULATA. 773 vance obliquely forwards towards tbe middle line of the body, those arising most anteriorly being the longest. The muscle extends forwards more than halfway from the pubis to the sternum. Transversus perinei (fig. 14, T.Pr.). This is a thick triangular muscle, arising from the side of the os cloacae and from the tendinous arch before mentioned passing to the ilium. It fuses more or less completely with the posterior part of the origin of the semimembranosus. CAUDAL MUSCLES. The essential nature of the true caudal muscles is best seen at about the middle of the tail (fig. 4). There the muscular mass of each lateral half of the tail, is easily demonstrated to consist of four longitudinal series of muscular and tendinous cones, the series being placed one above another, and all the cones having their apices directed forwards. Fig. 4. N. z. h. Diagram of caudal muscular cones of the right side of the tail. 1. Dorsal lateral cone. 2. Upper median lateral cone. 3. Lower median lateral cone. 4. Ventral lateral cone. h. Inferior spine. K Neural spine. t. Transverse process, z. Zygapophyses. Four such cones appear to spring from each side of each caudal vertebra; but their length generally exceeds that of two such vertebrae. The base of each cone is aponeurotic, with the superficial part glisteningly tendinous. The apex of each cone is muscular. Each cone being hollow, it receives into its cavity the muscular apex of the cone next behind. The repetition of this serial enclosure gives rise to the four longitudinal rows of cones ; and as the aponeurosis of each cone is more or less incomplete on its external surface, the tendinous margins of the aperture appear as two glistening lines, which converge anteriorly; moreover, the bases of the cones being on the same vertical line, the appearance of numerous acutely zigzag |