LIASSIC DINOSAURS. Ui 



2 inclies 7 lines in length, with a moderate contour. The apical ridge and left 

 side of this bone have been broken away. 



Between the above-described dermo-neural and dermo-h^mal bones there was 

 the base of a lateral dermal bone, 3 inches 5 hnes in length, applied over the 

 eighteenth and part of the nineteenth caudal vertebrae, like that between the 

 twenty-first and twenty-second. The portion preserved in exposing these vertebras 

 is figui'ed in the interspace produced by their slight dislocation, into which it had 

 been wedged by pressm-e. I conceive it to have been the direct instrument of the 

 dislocation, receiving and transmitting the extraneous pressure ; and at a period 

 when the vertebrse 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 (PI. 

 56, fig. 1). From the evidence of the dermo-neurals and dermo-htemals, in sitif, 

 in the present series of vertebrae, the dermal bone above described could not be one 

 of these series displaced ; and I infer from it, and the evidence of a similarly situ- 

 ated 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 vertebrge ; 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 two 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 avei'age 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 PI. 55, 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 vertebras, is the 

 base of a dermo-lateral bone, 3 inches 3 lines in length, 2 inches 2 lines in breadth, 

 the sides converging at an open angle, but with their terminal ridge broken off. 

 This representative 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 (hifimal) 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 quarry- 

 ing operations. It is probable, therefore, that the dermo-lateral bones of the left 

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