LOWER LIAS. 
11 
the haemal arch and spine are reduced to a length of 1 inch 2 lines ; the spine pro- 
gressively decreases to the thirty-second vertebra, beyond which the haemal 
element ceases to be developed. 
The centrum of the twenty-seventh caudal (Tab. IX, 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 
( 2 ) are 9 lines in length ; the neural spine (ns) is 1 inch in length above the zygapo- 
physial surfaces, its summit penetrates the base of a superincumbent dermal 
bone, and the haemal spine (^) 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, showing the coalesced neural arch (?*), 
from which the processes have been broken away, is figured in Tab. IX, fig. 6, 
the hmmal 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 (?js) behind, like its peak; and still 
giving off the pair of long and slender prezygapophyses (z) from its fore part, 
which clasp the spine or peak of the antecedent vertebra. 
The thirty-five caudal vertebrae, of wdiich 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 vertebrae 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-vertebrae include, as has been shown, four sacral, one lumbar, 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 tw'enty-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 approximate estimate of the total length of the individual 
affording the before-detailed osteological characters of Scelidoscmrus as not 
exceeding 12 feet from the snout to the end of the tail. But detached frag- 
ments of the fossilized skeleton of other individuals from the Lower Lias of 
Charmouth indicate a larger size, and that the present is not that of a mature 
Scelidosaur. 
