LIASSIC DINOSAURS. ]09 



spine expands to twice tliat extent, witli an obtusely rounded termination. In 

 the twenty-seventh caudal vertebra the haemal arch and spine are reduced to a 

 length of 1 inch 2 lines ; the spine progressively decreases to the thirty-second 

 vertebra, beyond which the hfemal element ceases to be developed. 



The centrum of the twenty-seventh caudal (PI. 56, fig. 5, 27) is 1 inch 10 lines 

 long; the anterior surface is 1 inch in depth, 1 inch 2 lines in breadth. The 

 coalesced base of the neural arch has an extent of 1 inch ; the prezygapophyses 

 (j) are 9 lines in length ; the neural spine (««) is 1 inch in length above the 

 zygapophysial surfaces, its summit penetrates the base of a superincumbent 

 dermal bone, and the hfemal spine (h) has a similar relation to the dermal bone 

 below. But both dermal bones may have been pressed nearer to the vertebra 

 than in the living animal as the soft parts became dissolved away. The thirty- 

 second caudal vertebra is 1 inch 4 lines in length, with a terminal breadth of 

 9 lines and a middle breadth of 6 lines. Its neural surface, showinsr the 

 coalesced neural arch («), from which the processes have been broken away, 

 is figured in PI. 56, fig. 6, the haemal surface is represented at fig. 7, with the 

 last haemal arch (/;), which is not quite closed above. The thirty- fourth caudal 

 vertebra (ib., fig. 8), is 1 inch 2 lines in length; the breadth of its front articular 

 end is 7 lines. The anchylosed neural arch has a basal extent of 9 lines ; it is 

 convex across the middle, like a saddle, rising into a short pyramidal process (ns) 

 behind, like its peak ; and still giving off the pair of long and slender prezygapo- 

 physes (?) from its fore part, which clasp the spine or peak of the antecedent 

 vertebra. 



The thirty-five caudal vertebra, of which the principal distinctive characters 

 have been above described, give a total length of 5 feet 8 inches 3 lines. The 

 extent of dislocation between a few of these vertebrae would make a deduction 

 of about 2 inches from the above extent ; but the few vertebra missing from the 

 end of the tail, and reduced, as shown by parts preserved, to slender centrums, 

 may, probably, have carried the length of the tail to about 6 feet. 



The trunk-vertebrge include, as has been shown, four sacral, one limabar, 

 sixteen dorsal, and seven, or at least six, cervicals, and these vertebrae average 

 each a length of 2 inches ; the total length of the vertebral column of the trunk, 

 estimated as including twenty-eight vertebrae, would be, on the above average, 

 4 feet 8 inches, or, allowing for intervertebral soft parts, 5 feet at the utmost in 

 the recent animal. 



The length of the head can scarcely have exceeded, more probably fell short 

 of, 1 foot. 



Thus we obtain an appi'oximate estimate of the total length of the individual 

 affording the before-detailed osteological characters of SceUdosaurus as not 

 exceeding 12 feet from the snout to the end of the tail. But detached frag- 



