The transverse and spinous processes of the sacrum are represented by three slender plates of bone, which, approximating as they pass backwards, are united to form a septum, extending down the median line of the sacrum to the taiL A channel is formed on each side of this septum by a thin flat plats of bone, which, arising from the posterior and superior part of the isehium on each side, is bent over the back part of the sacrum and fixed to an arched and prominent plate of bone, which is extended from this septum outwards to form a junction with it. The channels thus produced are bounded below by the sacrum, on the inner sides by the septum, on the outer sides by the ascending plates of bone just described, and above by the junction of both. From this union a short Osseous stem issues hori zontally on each side, and expands into a flattened circular plate of bone, to the rough surface of which, as well as to the tuberosity of the ischium below, portions of the truncated exterior of the animal are finnly attached.
The under surface of the sacrum is broad and flattened, and marked by an indistinct central ridge. The pelvis is open in front, the oissa pubis on each side do not incline inwards, hut descend at right angles from the horizontal surface of the sacrum. In the circumstance of the pelvis being open there is a second resemblance to tho bony structure in birds.
The cervical vertebrc 7, the first large, the articulating surface broad ; the 2nd, 3rd, and 4th very firmly ossified together, pierced with foramina for the passage of the cervical vessels; the 5th united to the 4th on the under surface only ; the 6th and 7th slender and separate, allowing the head great freedom of motion upwards ; the whole of the last six grooved on the under surface, in the line of the passage of the oesophagus. Dorsal vertebra; 11, the spinons process of the first slender, three-eighths of an inch long, the others diminish gradually in length, but increase in size ; all directed backwards. The first rib is very broad, and from the 2nd to the 8th the ribs of the Chlamyphorus, like those of birds, are firmly united to the sternum without the intervention of an elongated cartilage; and, again like those of birds, aro also supplied with a false joint, at the distance of about two-thirds of their length from the spine to the sternum. Tho 0th, 10th, and 11th being false ribs are united in the usual way to each other, and to the 8th by elongations of cartilage from their extremities. The portions of ribs intervening between tho false joints and the sternum are in the 6th, 7th, and 8th ribs, consolidated, broad, flattened portions of bone, which form the boundary of the anterior and lateral parietes of tho thorax. The first bone
of the sternum is broad and flat, the superior surface regularly concave, the inferior irregularly convex. Upon the anterior edge of the sternum are two prominences to which are attached the extremities of each clavicle. From each of these articulations a slightly elevated ridge proceeds backwards along the inferior surface of the sternum, converging towards the centre, where they become united, and form a prominent crest The lateral edges of this first bone of the sternum are articulated at its anterior extre mity to the first and broadest rib; from this part the bone suddenly The caudal vertebrae aro 14 in number ; the transverse pro cesses of the last four are elongated, to support the thin dilated lateral edges of the paddle or spatular extremity of the tail. Large muscles are imbedded in the two cavities formed on the upper surface of the sacrum by its septum and the two lateral elevated portions of the ischium before described ; and there are antagonist muscles of equal size on the under surface. The tendons of these muscles were inserted on the upper and under parts of the caudal vertebnc, giving great power tail, which is probably exercised in remov ing backwards the loose eon!' accumulated under the belly of this burrowing animal by the action of the fore legs, and fur which purpose the expanded and flattened extremity seems well calculated.
The scapula bee its superior margin straight, ending in a notch of great size ; the base rounded ; the inferior margin concave, and the posterior inferior angle considerably elongated; the corticoid process but little produced, the spine elevated, the acromion very long, passing forwards, downwards, and inwards, over the head of the humerus, to be articulated to a long and slender but perfect clavicle. There is a second spine of smaller size, parallel to but beneath the true spine. The humerus is three-fourthsof au inch in length, large, and broad ; the deltoid crest prominent ; between which and the external condyle a deep groove in formed for the lodgment of muscles, &c.; both condyles very much elongated transversely ; the inner con dyle perforated above; the edge rising from the external condylo acute. The radium small, and seven-sixteenths of an inch in length; tho ulna flattened,, concave upwards, the oleeranon nearly as long as the ulna, horizontally flattened also, and presenting a superior con cave surface, ending in a curve pointing downwards. The feet furnished with aesamoid bones for the insertion of the tendons of the flexor muscles.