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VII. Supplemental Note on Pol acanthus Foxii, describing the Dorsal Shield and 
some Parts of the Endoskeleton , imperfectly known in 1881 . 
By J. W. IIulke. F.R.S. 
Received December 14, 1886,—Read January 18, 1887. 
[Plates 8, 9.] 
In a former paper,* descriptive of the type remains of Polacanthvs Foxii, some 
account was given of its dermal armour, but the description was unavoidably very 
incomplete, owing to the extremely fragmentary state of the parts originally 
composing it. Broken up by its discoverer into pieces small enough for convenient 
stowage and transport in bags from the cliffs to the village of Brighstone, two-and- 
a-half miles distant, and then uncared for during fifteen years, the great dorsal shield, 
when after Mr. Fox’s death his collection was acquired by the British Museum, was 
represented by several hundreds of disconnected pieces, many of these being of less 
size than one cubic inch. It was also evident that many had been lost. In this 
mutilated condition the reconstruction of the shield appeared hopeless, but at length, 
under the guidance of the heads of the Palaeontological Department, this has been 
accomplished by Mr. Hall and Mr. Barlow (“ Masons ”), who brought to the task a 
painstaking perseverance and skill worthy of the highest praise. Although now, 
doubtless, much less complete than when laid bare in the cliff by Mr. Fox, the 
reconstruction (which has consisted strictly in a faithful reunion of the disconnected 
scattered fragments) renders very intelligible the discoverer’s first impression, viz., 
that “ he had before him the carapace of a gigantic turtle,” and it confirms his opinion 
of the position of the shield, viz., that it covered the rump and loins. The dimen¬ 
sions of the shield, given by Mr. Fox in a MS. note, 3 feet 3 inches by 3 feet, were 
taken roughly in the cliff before the shield was broken up. In its restored condition 
its breadth is 108 centims. in front, 105 centims. at its middle, and 48 centims. 
posteriorly, and its length is 90 centims. 
The relation of the shield to the pelvic bones makes it evident that the carcass 
was lying on its belly when it sank into the ooze, and that the shield was later 
crushed down upon the endoskeleton and flattened out. 
In its present state the outline of the shield forms a long oval figure, from which 
an anterior segment has been removed through a line parallel to its shorter axis. It 
* ‘Phil. Trans.,’ 1881 (vol. 172), p. 653. 
MDCCCLX XXV ri. —B. 
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