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Show 1896.] ANATOMY OF PETROGALE XANTHOPUS. 687 towards the head at their ends; they are small on the 1st and 2nd vertebrae, but rapidly increase afterwards. The anapophyses begin on the last three thoracic vertebra) and disappear on the last two lumbar. Fig. 3. - a - i r a r xmumwstmmtmsssei^asBlli 1st lumbar vertebra of Petroyale, with hypapophysis (H). The Clavicle has the usual single forward curve. The Scapula resembles that of Macropus in the absence of any sign of a metacromial process ; a small metacromion is, however, found in Bypsiprymnus. The Humerus is chiefly remarkable in that it shows all or almost all the centres of ossification; they consist of the following: - 1, head; 2, greater tuberosity ; 3, lesser tuberosity (quite distinct); 4, shaft; 5, internal condyle; 6, trochlea and capitellum; 7, external condyle. The centre for the internal condyle takes no part in the bridge of bone enclosing the supra-condylar foramen. The Radius and Ulna show all the epiphyses, but that for the upper end of the radius is nearly united to the shaft. The upper epiphysis of the ulna merely forms a cap to the olecranon. The Carpal bones correspond to Owen's description. In the Pelvis the three parts of the os innominatum are completely fused, but there is an epiphysis on the crest of the ilium and on the tuberosity of the ischium, the latter stretching along as far as the subpubic bone, with which in more adult animals it coalesces; there is also a slight ossific deposit in the centre of the pubic symphysis. No special centre is seen for the origin of the rectus femoris. The Femur shows the following epiphyses : - 1 , head ; 2, great trochanter; 3, upper part of lesser trochanter ; 4, shaft; 5, lower extremity. The epiphyses for the head aud great trochanter meet on the upper surface of the neck. The outer side of the posterior part of the external condyle is lipped and forms a groove for the reception of the elevation on the posterior part of the head of the fibula during extreme flexion of the knee-joint. The Patella is almost entirely cartilaginous, but a small bony deposit is seen in the centre. The Tibia shows the following centres : - 1 , head ; 2, upper part of cnemial crest where the ligamentum patellae is attached; 3, shaft; 4, lower extremity. In studying the ossifi- |