660 
MR. J. W. HULKE OR THE POLACANTHUS FOXII. 
The resemblance of their dermal spines is very close, and their tibiae are remarkably 
alike. Indeed, I do not know in any public or private collection any bone which the 
tibia of Polacanthus so nearly resembles as the type tibia of Hylceosciurus preserved 
in the national collection and a tibia which a few years since I brought before the 
Geological Society and provisionally referred to this dinosaur.* It was obtained 
from Brixton Bay, the locality which yielded these remains of Polacanthus. We may 
not safely compare the metatarsals of this skeleton with those accredited to Hylceo- 
saurus, since the type specimen (No. 2556 Brit. Mus. Cat. figured in the Brit. Foss. 
Kept., Monog. Hylceosaurus, plate xi.) is only conjecturally assigned to it, and may 
have belonged to a very different animal, for the length and slenderness of these meta¬ 
tarsals are not in harmony with the Hylseosaurian tibia so short and with such 
expanded articular ends. Neither are the type specimens of sacrum and the dis¬ 
connected vertebrae in the British Museum available, because their reference to Hylceo- 
saurus is also conjectural and still requires confirmation. Such comparison, whatever 
its value may finally prove, however, shows that the sacrum of Polacanthus is much 
more massive and the thoracic vertebrae are longer and less stout than those reputed 
Hylseosaurian fossils. 
Explanation of Plates. 
PLATE 70. 
Fig. 1. Posterior view of a vertebra from the front of the chest, t 
Fig. 2. Oblique lateral view of the same. 
Fig. 3. Fragment of a large keeled scute with grooved margin and submarginal rings 
of tubercles. 
Jc. Beginning keel. 
Fig. 4. Sectional view at x in fig. 3. (This and fig. 3 are slightly reduced.) 
PLATE 71. 
(All the figures in this plate are represented rather less than one-half 
their natural size.) 
Fig. 1. Ventral view of sacrum and anchylosed lumbar vertebrae. The numerals 1-5, 
s., mark the sacral, and the letters l.l.l. the lumbar vertebrae. 
ng. Nerve-groove. 
* ‘ Quarterly Journal Geological Society,’ vol. xxx., 1874, plate xxxi., figs. 1, 2. 
f In all the representations of vertebrae, c. Centrum, ns. Neural spinous process, prs. Prcezyga- 
pophysis. psz. Postzygapophysis, cl. Diapophysis, p. Parapophysis. c.c. Capitulum cost®, r. Rib- 
shaft. 
