ELOriDJS. 
35 
and much tapering at the symphysis. The artieulo-angular 
element is very short, with a large concave articular 
facotte for the quadrate, best seen on the right side. Tho 
dentary ( d .) hears a spaced series of teeth slightly larger 
even than the largest on the maxilla. Of the opercular 
apparatus only fragments remain. The preoperculum 
seems to have been very narrow, and this is probably the 
displaced arched bone on the right side of the fossil, not 
shown in the figure. Purchased, 1864. 
4055 . Slab of chalk exhibiting the imperfect hinder half of a larger 
skull associated with a quadrate, vertebra, and other 
fragments, provisionally referred by Agassiz, loc. cit., to 
Hypsodon lewesiensis ; Chalk, Sussex. The skull and 
quadrate bone are figured by Agassiz, loc. cit. The cranial 
roof exhibits the characteristic median depression. Tho 
vertebra are shorter than deep and strengthened by deli- 
cate longitudinal ridges. A fragment of jaw on the same 
slab bears traces of large hollow teeth like those of Por- 
theus ; but, if the determination here proposed he correct, 
this cannot have belonged to the same fish as the skull. 
Mantell Coll. 
49078 . Hinder portion of small skull, with six anterior vertebral 
centra in position, partly invested with pyrites ; probably 
from the Lower Chalk of Kent. The portion of cranial 
roof is shown from above, of the natural size, in PI. V. 
fig. 2 ; while two of the vertebral centra are represented 
in side-view and from below in figs. 2 a, 2 b. The 
sutures between the various elements of the cranial roof 
are distinct and arranged as already described in the type 
specimen. The constitution of the otic region is also 
well shown. The anterior vertebral centra do not exhibit 
lateral pits, except one facotte near the ventral border 
for the articulation of the rib (r.). Their ventral face, 
however, is pitted and strengthened with longitudinal 
ribbings. Mrs. Smith’s Coll. 
Thrissopater (?) megalops, sp. nov. 
[Plate VII. fig. 4.] 
Type. Imperfect head ; British Museum. 
A species about as large as the type, known only by the 
head, opercular apparatus, and scales. Posterior suborbital plates 
