346 Messrs. Hancock & Atthey on Reptile- and Fish-Remains 
XLV.—Notes on the Remains of some Reptiles and Fishes 
from the Shales of the Northumberland Coal-field. By 
ALBANY Hancock, F.L.8., and Taomas ATTHEY. 
[Continued from p. 278.] 
[Plates XIV., XV., XVI] 
Rhizodus Hibberti, sp., Agassiz. oa 
The teeth of this species have not yet been found in the 
shales of our neighbourhood; but large scales which appear to 
belong to it are not by any means uncommon at Newsham 
and Cramlington. They are rarely found perfect; sufficient 
examples have, however, been obtained to enable us to identify 
them with the scalesof Lhizodus Hibberti described by Dr. Young 
in vol. xxii. p. 599 of the ‘ Journal of the Geological Society.’ 
The largest we have seen measures three inches in diameter ; 
they usually appear quite thin, and are of an irregularly 
rounded form with the front margin a little flattened, the pos- 
terior a little produced, and the sides only slightly arched. 
The surface is marked with numerous sharp concentric lines 
of growth and minute, close, radiating strie, requiring a good 
lens to show them. ‘There are also a few distant delicate 
ridges, extending from the centre to the anterior border. 
Such scales are undoubtedly in an imperfect condition. 
When complete, they are considerably thicker, and the under 
surface has a smooth bony appearance, exhibiting nevertheless 
decided concentric lines of growth, a subcentral elongated 
boss, and numerous small pits, particularly on the posterior 
portion, which, however, we have never seen in a good con- 
dition. On the posterior or exposed area there are a few ob- 
secure, irregular, radiating ridges, which are rendered still more 
indistinet by the granular tubercles that are scattered over the 
surface. ‘The smaller scales, which are usually about one inch 
and three-quarters long and scarcely one and a half inch wide, 
have all the characters of the large scales; but they are ge- 
nerally more elongated in form, and the minute radiating strie _ 
are coarser. 3 
Besides these scales, several bones have occurred at News- 
ham, which, from the peculiar surface-sculpture, most probably 
also belong to this powerful fish. We were anxious to prove 
this by comparing them with some authenticated fragment of 
the bone of Rhizodus showing the surface-ornament, but have 
failed in our endeavour. They agree, however, in this respect 
so well with the descriptions, that we cannot hesitate to assign 
them provisionally to this species. 
Of the two most remarkable bones: of this collection, one 
