402 On some British Upper Jurassic Fish-remains. 
hitherto been recorded from the Upper Jurassic of England, 
one from the Oxford Clay of Yorkshire * and two others 
from the same formation near Oxford t. It is thus interesting 
to note that a fourth specimen has been discovered more 
recently by Mr. Thomas Jesson, F.G.S., in the Oxford Clay 
of St. mo This is a well- preserved tooth, shown of the 
natural size in fig. 5, and considerably differing from each of 
the others, 
The new fossil has a shallow and somewhat crimped root ; 
and the crown consists of a very large principal cone, followed 
by three secondary cones decreasing in size, with a minute 
posterior denticle. The enamel is quite smooth, and the 
gracefully sinuous anterior margin of the principal cone 
exhibits only the feeblest crimping, no denticulation. 
The specific determination of the isolated teeth of Selachian 
fishes is, of course, nearly always a matter of speculation ; 
but it is convenient to have names for purposes of quotation. 
As the new tooth, therefore, does not appear to differ in any 
essential respect "from some of the specimens found in the 
Oxfordian, Corallian, and Lower Kimmeridgian of the Con- 
tinent, commonly referred to Notidanus Muenster?, it seems 
advisable to provisionally record this specimen under the same 
name. 
Form. and Loc. Oxfordian; St. Ives, Huntingdonshire. 
EXPLANATION OF PLATE XVIII. 
Fig. 1. Caturus angustus, Agassiz ; fish wanting head, lateral aspect, one 
half nat. size. —Portlandian ; Garsington Hill, Oxford. { Wor- 
cester Museum. | 
. Gyrodus punctatus, Agassiz; portion of vomerine dentition.— 
Corallian (Lower Calcareous Grit); Browse Pit, Malton, 
Yorkshire. [Malton Museum. | 
Fig. 5. Ditto; left splenial dentition.—Corallian (Lower Calcareous Grit) ; 
Malton. {Malton Museum. ] 
Fig. 4. Ditto; large right splenial dentition, apparently crushed.— 
Corallian (Lower Caleareous Grit); Browse Pit, Malton. 
| Malton Museum. | 
Fig. 5. Notidanus Muensteri, Agassiz ; tooth, outer aspect.—Oxfordian ; 
St. Ives. [ British iinerenreace no. P. 6734. ] 
Fig. 
bo 
[ Figs. 2-6 are of the natural size. ] 
* Notidanus serratus, Fraas, Smith Woodward, Geol, Mag. [3] yol. iii. 
(1886), p. 212, pl. vi. fic, te 
at Notidanus Daviesi, “Smith W oodward, tid. p. 212, pl. vi. figs. 8, 9. 
