. Bulletin - United States National Museum. Science. OSTEOLOGY OF CAKNIVOROUS DINOSAURS. 99 longer than high, whereas in the upper Cretaceous genera mentioned above the anterior centra are as high as long. In passing backward from the sacrum there is a gradual shortening of the centra, and they become more and more cylindrical in form, though all except the terminal ones have flattened sides. The vertebral centra are deeply concave on both sides and below, the anterior ones being shallowly grooved longitudinally on the ventral side as shown in figure 2, plate 22. The neural spines are unusuall
. Bulletin - United States National Museum. Science. OSTEOLOGY OF CAKNIVOROUS DINOSAURS. 99 longer than high, whereas in the upper Cretaceous genera mentioned above the anterior centra are as high as long. In passing backward from the sacrum there is a gradual shortening of the centra, and they become more and more cylindrical in form, though all except the terminal ones have flattened sides. The vertebral centra are deeply concave on both sides and below, the anterior ones being shallowly grooved longitudinally on the ventral side as shown in figure 2, plate 22. The neural spines are unusually high, relatively narrow antcro-posteriorly, with flattened sides and ending above in a slightly expanded rugose end. The expansion is not only slight in transverse diameter, but expands pronouncedly fore and aft. Proceeding posteriorly the shaft of the spinous processes narrows more rapidly than they shorten in length, thus making them tall and slender. Their point of origin also shifts from the middle of the centrum to a point entirely above the posterior half. They rapidly de- crease in height on the median part of the series, the last distinct spine being on the thirty-first caudal. On account of their crushed condition the spines posterior to the twenty-eighth do not show in the lateral view in plate 30. The transverse processes on caudal 1 are directed backward at an acute angle to the centrum, but do not unite with the ilia, as apparently indicated in figure 1, plate 21. These proc- esses on the succeeding vertebrae are long, broad, thin vertically, and termi- nated by straight ends without any especial expansion. On the second caudal they are directed backward at an angle of 45°, but they gradually assume a more direct outward position at the same time; diminishing in size, they end abruptly, the last one appearing as a thin pointed process on the thirty-third vertebra, whereas in Gorgosaurus libratus Lambe they end with the fourteenth caudal from the sacrum. In fact,
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