284 
DR. MANTELL ON THE OSTEOLOGY OF 
Dermal boties, Plate XXXII. — Several dermal bones have been discovered since my 
last communication on this subject, some of which are clearly referable to the Hylseo- 
saiirus, while others may with great probability be assigned to the Iguanodon, from 
their obvious difference from those found associated with the bones of the former 
reptile. Some dermal spines or tubercles resembling that which I figured and de- 
scribed as the horn of the Iguanodon in my “Fossils of Tilgate Forest,” have been 
found at Hastings, and in the Isle of Wight. One remarkably fine example of a 
conical dermal tubercle or horn, in which the core or base is ossified, was obtained 
from the Wealden at Ridgway near Weymouth, by Mr. Shipp of Blandford, and several 
bones of the Iguanodon were found in the same locality ; it is figured in Plate XXXII. 
fig. 24. Several somewhat angular bones, of coarse texture, 5 or 6 inches long, 
which resemble in form the spinous warts seen in the Amblyrhynchus and other 
Iguanidse, have likewise been obtained from Sandown Bay. In the absence of proofs 
derived from direct connection or contiguity with known parts of the skeleton, it is 
useless to attempt appropriating these dermal appendages to particular Saurians. 
But in the case of the Hylaeosaurus the dermal bones peculiar to that animal are 
easily recognizable ; for not only have I found them in the typical specimen of this 
reptile discovered in 1832*, but likewise in the beautiful series of vertebrae already 
referred to'f-, Plate XXXII. fig. 22 ; in which the discoidal and oval scutes are 
situated on each side the spinous processes of the vertebrae. 
The same fossil contains, at the anterior part, portions of large angular spines re- 
sembling those described in my former memoir;};. As the correctness of my opinion 
that the large flat spines in the first-discovered specimen of the Hylaeosaurus were 
dermal, and extended down the back as a dorsal fringe, has been questioned by 
Professor Owen I beg to state, that since my former communication I have submitted 
sections of one of these spines to microscopical examination, and if identity of 
internal structure be of any value, my interpretation is substantiated ; for the same 
remarkable organization is present as in the admitted dermal scutes, namely, 
“ straight spicular fibres decussating each other in all directions, and seeming to re- 
present the ossified ligamentous fibres of the original corium||.” 
Summary . — The facts described in this communication will, I trust, be regarded as 
a valuable addition to our knowledge of the osteological structure of one of the most 
remarkable herbivorous terrestrial quadrupeds that ever trod the surface of our 
planet. With the exception of the cranium, sternum, and the bones of the fore-arm, 
carpus, and tarsus, the entire skeleton may now be considered as determined. In 
the present memoir the pectoral arch and the arm are for the first time described 
* Geology of the South-East of England, PI. V. t Ante, p. 277. 
X Philosophical Transactions, 1841, p. 150, Plate X. figs. 1, 2, 3, 4. 
§ See Reports on British Fossil Reptiles, 1841, p. 115. 
II See Wonders of Geology, sixth edition, p. 438. Mr. Bowkrbank, Mr. Williamson, and other eminent 
microscopical observers, to whom I gave specimens of the spines, concur in the statement that the structure of 
these bones is identical with that of the dermal scutes, Plate XXXII. fig. 23. 
