352 PLEISTOCENE GEOLOGY OF THE THAMES VALLEY.
Esox lucius, Linn. (Pike). A number of teeth of various
sizes, the largest measuring 13.0 mm. or more in length, and
having the compressed crown with sharp edges, so characteristic
of the pike, are believed to represent this species at Grays. The
same form has long been known to occur at Ilford and in beds of
similar age elsewhere, as well as in the Norfolk Forest Bed.
Leuciscus. Several pharyngeal bones and numerous
isolated teeth of Cyprinoid fishes are without doubt referable to
this genus ; but while some of the specimens can be definitely
assigned to species, most of the isolated teeth can only be
generically named or at best placed in species provisionally.
Leuciscus rutilus, Linn. (Roach). Two pharyngeal
bones, each with a single row of teeth and these of the forms
found in the Roach, supply as good evidence as could be
expected of the presence of this species at Grays ; and it is
almost certain that the greater number of the isolated teeth also
belong to this form, which has been recognised in other British
Pleistocene beds and also in the Norfolk Forest Bed.
Leuciscus vulgaris, Flem. (Dace). Four small pharyngeal
bones, each with two rows of teeth, which are comparatively
long and with somewhat hooked extremities, are believed to be
rightly placed with L. vulgaris, and certain of the isolated teeth
probably belong here also. I am not aware that this species has
before been found in Pleistocene beds.
Leuciscus erythrophthalmus, Linn. (Rudd). A single
isolated crown, which is long, slender, curved and strongly
crenulated, is the only specimen which can at present be placed
in this species. Evidence of the Rudd was found in the Norfolk
Forest Bed and it has also been met with in Pleistocene beds at
Hitchin.
Anguilla ? anguilla ? Linn. (Eel). A single imperfect
vertebra has the neural arch strongly developed and forming a
bony tube as long as the centrum itself. A similar condition of
the neural arch is found in certain of the vertebrae of the common
Eel, and it seems probable that our specimen represents that
species which has not hitherto been recognized as a fossil. It
may seem hazardous to record a species, even with doubt, upon
such slender evidence ; but I feel justified in so doing in order
that attention may be directed to the possible occurrence and so
further evidence be sought for.