6 FOSSIL REPTILIA OF THE 



The ribs of the twelve anterior dorsal vertebrae show both the head and the 

 tubercle, the neck becoming gradually shorter in the last three. In the seventh 

 vertebra the extent of the rib from the head to the tubercle is 2 inches 9 lines. 

 In the tenth vertebra it is 1 inch 7 lines. The rib presents a shallow canal along 

 its posterior surface; it is nearly an inch in thickness. An extent of upwards of 

 10 inches of the body of the rib {pi., Tab. II) is preserved on the right side of this 

 portion of the thorax of Scelidotherium. 



The anterior dorsal vertebras have been partially dislocated, especially the 

 fourth from the fifth, apparently by pressure acting through the scapula (51) upon 

 the diapophysis and spine of the fifth dorsal. Beyond the scapula the vertebrae 

 have retained their natural position and connections, which seems to indicate the 

 action of pressure whilst decomposition of the soft parts was going on in the carcass. 

 Nine of the consecutive vertebrae in the fourth block occupy the extent of 1 foot 

 9 inches. The breadth of the last of these vertebrae (Tab. II, d 10 ), across the diapo- 

 physes (d), is 5 inches 4 lines. The total height of the eleventh dorsal vertebra 

 (Tab. 5, fig. 1) is 6' inches. The breadth of the centrum at the fractured part, near 

 the anterior surface, is 1 inch 6 lines. The depth of the centrum, from the floor of 

 the neural canal, is 2 inches. The breadth of the neural arch across what are called 

 the "pedicles,'' is 1 inch 8 lines. The height of the neural spine is 2 inches 6 lines. 



As the vertebrae approach the sacrum the bodies gradually increase in depth, 

 without gaining in breadth, until at the last dorsal the centrum, near its middle part, 

 measures 2| inches in vertical and 1 inch 7 lines in transverse diameter ; a slight 

 longitudinal impression on each side produces the contour of the transverse vertical 

 section figured in Tab. V, fig. 2. The neural canal here gives a triangular section, 

 with the apex downward and sinking into the substance of the centrum, but the 

 sutural limit between centrum and neural arch are indiscernible. The diapophyses 

 decrease in breadth and also in length, and now support the rib by a terminal, 

 slightly notched, articular facet. The ribs, here with simple heads, become shorter 

 and less curved; a few, as in Tab. IV, fig. 1, pi y have suffered fracture, with very 

 little displacement. In different parts of the matrix of the blocks (Tabs. II and 

 IV) are portions of long and slender bones, which are, most probably, abdominal 

 ribs. 



In the sixth block the hinder half of the last dorsal and one lumbar vertebrae 

 are associated with the pelvis; the lumbar vertebra (Tab. VI, l) had been dislo- 

 cated downwards from its articulations with the sacrum. 



The four vertebrae of this part (Tab. VI), with the iliac bones (62), are preserved 

 almost in their natural relative positions, the sacral vertebrae having their neural 

 spines and transverse processes exposed. Those of the first sacral (si, </, pi) stand 

 out horizontally and transverse to the axis of the body ; a slight swelling {d), about 

 one inch from their origin, may indicate the point of confluence of the pleurapo- 



