LOWER IJAS. 
2] 
worm-eaten, by narrow curved grooves with intervening small, oblong, and circular 
pittings. The texture as exposed by the fracture was compact, reflecting a lustre. 
Between the twenty-ninth and thirtieth vertebrae there was the basal part of a 
similarly shaped dermal bone, 1 inch 9 lines in extent, with a basal breadth of 
9 lines. It lies upon the right side of the coadopted halves of the neural arches 
of these vertebrae, but may have been displaced from the median line, and this is 
more probable as the base of a dermal bone crossing the articulation between the 
centrums of the same caudal vertebrae, has also been pressed towards the right 
side, on which the carcass of the reptile appears to have rested in the matrix. 
But any doubt as to the relations of the dermal bone above indicated was dissi- 
pated by the better preservation of those found in connection with the twenty- 
seventh and twenty-eighth caudal vertebrae (Tab. IX, fig. 2), and which are 
represented of the natural size in figure 5 of the same plate. 
The dermo-neural bone was found fractured, with a slight displacement of 
the back part of its base : when entire, it had a longitudinal extent of 3 inches 
6 lines, and a vertical one of 2 inches. The base is hollow, and has been crushed by 
the lateral pressure ; but seems to have had a breadth of nearly an inch. The 
sides converge to the upper margin, which describes a bold convex curve from 
before backwards, along two thirds of the contour, and then descends in a straighter 
line obliquely backward to the hinder angle of the base. This dermal bone extends 
from above the prezygapophyses ( »; ) of the twenty-seventh caudal vertebra to the 
fore part of the spine of the twenty-eighth. On removing part of the side of 
the base of the dermo-neural bone the spine (ns) of the twenty-seventh vertebra 
was seen to have penetrated the basal cavity, as far as that extended into 
the substance of the dermal bone ; but I incline to think that fibrinous or other 
soluble tissue intervened in the living reptile, and that the position of some 
of the more anterior dermo-neurals, situated at a higher level above the neural 
spines, was the more natural one. 
The dermo-haemal bone (ib., d h) presents a longitudinal extent of 2 inches 
3 lines, with a vertical one of 13 lines, and a basal breadth of about 9 lines. 
The haemal spine of the twenty-seventh vertebra (7t), seems also to have entered 
a hollow in its base, where it w'as exposed by removal of part of the left wall of 
the basal cavity. But this had been pressed up to the under part of the cen- 
trums, almost touching the posterior half of the twenty-seventh and the con- 
tiguous two thirds of the twenty-eighth caudal vertebrae ; obliterating an interspace 
which should have been occupied by muscle, tendon, ligament, and other soft 
parts in the recent animal. 
The dermo-haemal spine below the twenty-fifth and twenty-sixth caudals differed 
only in its larger size from the succeeding one. Part of the base of the corresponding 
dermo-neural was preserved. 
