LOWER LIAS. 
23 
had been wedged by pressure. I conceive it to have been the direct instrument 
of the dislocation, receiving and transmitting the extraneous pressure; and at a 
period when the vertebrae in front and behind were sufficiently free in their bed to 
allow of being pressed close together, with obliteration of their natural interspaces 
originally occupied by the soft inter-articular material ; the extent of such inter- 
space is probably shown between the twenty-second and twenty-third caudals 
(Tab. IX, tig. 1). From the evidence of the dermo-neurals and dermo-heemals, 
in situ, in the present series of vertebrae, the dermal bone above described could 
not be one of either of these series displaced; and I infer from it, and the evidence 
of a similarly situated bone in a remoter part of the tail, that this appendage was 
defended by a series of lateral as well of upper and lower dermal ossicles, though, 
perhaps, in less number, and of a flatter figure, along the sides. 
The next dermo-neural in advance overlaps the sixteenth and the contiguous 
half of the fifteenth caudal vertebrae; but its hinder end, as well as a part of its 
summit, are broken away. What remains, measures 3 inches 4 lines in length, 
with a basal breadth of at least 2 inches. The margin of the base of all the above- 
described dermo-neurals describes a gentle convexity. 
As the dermo-neurals advance in position, they progressively acquire increase 
of basal breadth, to near the base of the tail, retaining the average length of 3| 
inches, with a small increase of height. Three dermo-neurals range along an 
extent of the five vertebrae (eleventh to fifteenth caudals) figured in Tab. VIII, 
fig. 3 ; and the same relative number and position are shown in the five antecedent 
caudals (ib., fig. 1, dn). 
On the right or imbedded side of the vertebrae, overlying the centrum of the 
fourteenth, and contiguous parts of the thirteenth and fifteenth vertebrae, is the 
base of a dermo-lateral bone, 3 inches 3 lines in length, 2 inches 3 lines in breadth, 
the sides converging at an open angle, but with their terminal ridge broken off. 
This lepresentative of the lateral series of dermal bones would seem to show that 
they had greater breadth and thickness than either those of the upper (neural) or 
lower (haemal) dermal series. The right side, where these additional indications of 
a lateral series of dermal bones are preserved, was that which was left imbedded in 
the matrix ; the left side being that which was exposed by the original quarrying 
operations. It is probable, therefore, that the dermo-lateral bones of the left side, 
with the exception of the few remains above noticed, were in the matrix so 
detached. The characters of the caudal vertebrae figured in Tabs. VIII and IX 
were displayed by careful removal of the matrix left adhering to the parts origi- 
nally exposed ; during which operation the portions of the dermo-lateral bones 
which had been" pressed inward, and contributed to the dislocation of the twenty- 
first from the twenty-second, and of the eighteenth from the nineteenth caudal 
vertebrae, were brought to light. 
