268 Messrs. Hancock & Atthey on Reptile- and Fish-Remains 
was only seven times the length of the cranium, which is about 
the proportion of these parts in Keraterpeton Galvani, a com- 
paratively short species, then Pteroplax must have been eight 
or nine feet long. 
This new genus, though it seems, as above stated, to be 
nearly related to Loxomma, resembles not a little, in the 
general form of the skull, as far as it can be determined, 
Dasyceps Bucklandi*. The concavity of the occipital margin 
and the two lateral cornua are very similar in both species ; 
but in the latter these processes or horns are more robust, 
and do not look so spine-like as in Pteroplax cornuta. The 
proportions and forms of the component bones, too, are very 
different; and the parietal foramen in Dasyceps is much nearer 
the occipital margin, as are also the orbits, which are likewise 
very much smaller. The resemblance, also, of these cranial 
bones to those of Keraterpeton cannot be overlooked, so far 
as they can be compared. The general form of the crown 
of the head, with the narrow projecting frontals and concave 
occipital margin, together with the ‘ postero-internal cornua,”’ 
are all remarkably alike in the two forms; but, from the defi- 
ciency of surface-sculpture in that animal, and its compara- 
tive smallnes, it would seem that they cannot be considered 
congeneric. 
Four left premaxillaries have been obtained; and all of them 
have a portion of the nasal bone attached, as well as several 
teeth more or less perfect. The premaxillary is about two 
and a half inches long, and upwards of half an inch wide; it 
is arched most strongly towards the anterior yu which 
is oblique and coextensive with the width of the bone; be- 
hind, it is prolonged, the articular portion being wedge-shaped; 
the surface is strongly sculptured into elevated anastomosing 
ridges and depressions; Bee they all exhibit two strong, wide, 
round grooves on the external surface, one of which passes 
from the front, the other from behind, converging and meet- 
ing at nearly a right angle, close to the alveolar margin. 
These grooves are similar to what have been denominated 
mucus-grooves in the Labyrinthodonts, and are exceedingly 
like those figured and described by Prof. Owen on the muzzle 
of Labyrinthodon leptognathust. And in this instance they 
seem to indicate the boundary of the nasal bone, which is ap- 
parently of a lozenge-form, probably somewhat prolonged 
backwards. Half the circumfererice of an external nasal ori- 
fice is distinctly perceptible in two of the specimens; it is cir- 
cular, and about one-quarter of an inch in diameter: the two 
* Memoirs Geol. Survey, 1859, p. 42. 
+ Trans. Geol. Soe. ser, 2. vol. vi. p. 417, pl. 48.-fig. 1. 
