LIASSIC DINOSAURS. 119 



At the thirty-first caudal vertebra, for example, there was attached to the back 

 part of the neui^al arch, and pressed rather obliquely to the left side, an elongated 

 triedral dermal bone, with the narrowest side or surface forming the base, and the 

 two broader or larger lateral surfaces converging at an acute angle to an upper 

 ridge. Much of this ridge on the fore part of the bone had been broken 

 away in the original exposure of the specimen ; the length of what remained was 

 1 inch 2 lines, with a basal breadth of 6 hues. The sides of the bone seemed as if 

 worm-eaten, by narrow curved grooves with intervening small, oblong, and cir- 

 cular 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 co-adapted 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 vertebrte 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 dissipated 

 by the better preservation of those found in connection with the twenty- seventh 

 and twenty-eighth caudal vertebras (PI. 56, fig. 2), and which are represented of the 

 natural size in figm-e 5 of the same plate. 



The dermo-neural bone (dn), 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 pressiu-e ; 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 hne obliquely backward to the hinder angle of the base. This dermal 

 bone extends from above the prezygapophyses {z) 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-h^mal 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 (h) seems also to have entered 

 a hollow in its base, where it was 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 



