from the Shales of the Northumberland Coal-field. 347 
approaches in form to the malar of the Alligator, and reminds 
one somewhat of the bone in Asterolepis considered by Agassiz 
to be a premaxillary*; but in our specimen the articular por- 
tion is wanting. ‘The other bone is apparently the posterior 
part of a mandibular ramus with a wide articular process at 
the hindermost part, not perfect though very distinctly dis- 
played. The former of these bones is quite four and a half 
es long, and upwards of one inch wide at the broadest 
part; it is thin in front, thickens backwards, and bends rather 
abruptly down at the posterior extremity, which is broken. 
Along the under margin there is a wide, flat, thin, squamous 
process, probably for the articulation of the maxilla; the op- 
posite margin is not perfect; but in a smaller specimen of the 
same bone a similar flat articular process extends from the 
— margin also. | 
he bone which we suppose to be the posterior portion of a 
mandibular ramus is nearly five inches in length and one and 
a half inch wide, including the lateral squamous expansions ; 
it is thin, flat, and rounded in front ; behind it is much thicker; 
and though the posterior extremity is wanting, the greater 
portion of the articular process is present; it has a wide 
oblique glenoidal surface. The lateral squamous expansions 
will undoubtedly articulate with the dentigerous bone. 
Other interesting bones have also occurred, some of which 
can be identified as jugulars. One distorted and folded mass 
comprises two large jugulars, apparently the pair of Sie 
plates. A considerable portion of one of them is well dis- 
played, exhibiting in very good condition the surface-orna- 
ment. Were this plate unfolded, it would be about seven 
inches long and two and a half inches wide. Three or four 
inches of what seems to be the posterior portion lies flat upon 
the matrix, and shows the contour quite perfectly. The plate 
is apparently equally thin throughout; and the outer margin 
seems, judging from the portion that is displayed, to be pretty 
vidlacly arched, and the posterior margin to be rounded and 
— a little forwards towards the inner border. 
nother bone, probably also a jugular, is worthy of notice. 
This appears to be an anterior plate; nearly one-half of it can 
be made out: it is symmetrical, having a stout angular midrib 
with two lateral wing-like expansions. When entire, it would 
be four and a half inches wide and one inch and three-quarters 
long. It is impossible to overlook the resemblance of this 
bone to the falda: plate of Asterolepis ; and, like it, this pro- 
bably fitted into the top of the arch formed by the junction of 
* Poissons Fossiles du Vieux Grés Rouge, troisisme livraison, p. 95, 
fab. 32. figs. 18,19. : 
25* 
