266 Proceedings of the Royal Society 
rounded snout; the external ornament of the hones of the cranium 
proper is rugose in character. The operculum is oblong, broader 
above than below, and ornamented with delicate ridges which 
radiate from the anterior-superior angle downwards and backwards 
over its surface ; the interoperculum is nearly square, and marked 
with ridges which for the most part pass horizontally over its surface 
from before backwards; the prasoperoulum is well developed. The 
jaws are stout; the broad part of the maxilla is ornamented with 
delicate and not very closely placed branching and anastomosing 
ridges, which for the most part tend to run parallel with its superior 
and posterior borders ; the striation of the mandible is close, the 
ridges running longitudinally, but the dentary margin is finely 
tuberculated. The teeth with which the jaws are armed are most 
peculiar in form and arrangement ; they are about to inch 
in length, slender-cylindrical in shape, but suddenly narrowed 
near the extremity to a sharply conical apex. Each tooth is first 
inclined a little inwards, then bent outwards at an obtuse angle, 
and again bent so that the apex comes to point upwards (or down- 
wards in the case of the maxillary teeth). They are nearly 
uniform, and arranged in one closely set row, inside which there 
are no larger teeth, nor have I seen any evidence of smaller ones 
outside. The branchiostegal rays are thirteen on each side, the , 
anterior of each series being broader than those behind, besides 
which there is a median lozenge-shaped plate in front. The bones 
of the shoulder girdle are well shown in most of the specimens, 
and like those of the face are ornamented externally with flexuous j 
branching and anastomosing ridges. 
The scales of the flank are slightly higher than broad, with 
gently concave upper, and convex flower margin ; the articular 
spine is well marked. On the under surface, the socket for the 
spine of the scale below is distinct, but the keel is obsolete ; the 
latter appears as we proceed backwards towards the tail, while 
the spine and its socket diminish and ultimately disappears. The 
posterior margin of the scale is finely and obliquely serrated. On 
the outer surface the margin overlapped by the scale next in front 
is very narrow ; the exposed area is in the most anteriorly situated 
scales, is ornamented with delicate and rather feebly marked ridges, 
best marked along the anterior and inferior margins with which 
