NEW ESSEX MARINE FISHES.
81
The examples of Neritina fluviatilis were small, but the
coloration, though not brilliant, was well developed. Limnea
pereger, though common, was dwarfed, 12 mm. being the
height of the largest example. Bithynia tentaculata and B. leachii
were scarce and dwarfed. Ancylus fluviatilis was very common
and of average size, whilst its ally, Velletia lacustris, was dwarfed.
The differences between the development of the various
species no doubt arises from the relative abundance of food, and
it is evident that these mollusca can exist without light.
If, as is probably the case, other water-mains which are still
in use contain a like abundance of molluscan life, it must consti-
tute a standing danger to the population using the water drawn
from such sources.
Mons. A. Locard2 has published a long list of species (so-
called) of mollusca from the water-mains of Paris, and all the
species that we have recorded are in his lists.
NEW ESSEX MARINE FISHES.
IN Dr. Laver's catalogue of the Fishes of Essex in the first
volume of the Victoria History, several species are included
which were not known locally when the Mammals, Reptiles and
Fishes of Essex was published in 1898. It seems desirable to
record these here for convenience of reference. We therefore
make the following extracts from the History:
Family DISCOBOLI.
Lepadogaster bimaculatus, Penn. Double-Spotted
Sucker.—Has been rarely recognised, but there is [? was] one
specimen in the Brightlingsea Marine Station, caught in the
mouth of the Colne.
Family BLENNIDAE.
Blennius gattorigine, Bloch. Gattorugine.—Mr. E. A.
Fitch records the capture of one specimen in the Blackwater, off
Stangate, in August, 1898. (See Essex Nat. xi., p. 143).
Family GADIDAE.
Gadus minutus, Linn. Power or Poor Cod.—Mr. E. A.
Fitch says that this is not rare at times in the Thames Estuary.
2 A. Locard " Malacologie des Conduites d'eau de la ville de Paris." Mem. Acad. Sci.
Lyon. Ser. III., Tom. II. (1893), pp. 341-416.