vi. PREFACE.
It is, I suppose, inevitable that, as the pursuit of
science becomes more widely spread, and investigations
more exact, alterations should be made in the nomen-
clature and classification of the various species. Such
changes, however, add immensely to the difficulty of
compiling a catalogue. In the nomenclature adopted
throughout these pages, I have to thank Professor Sir
William Flower, Director of the British Museum,
Natural History, at South Kensington, for valuable
assistance with the Carnivora, Rodentia, and Rumi-
nantia. In the orders Cetacea and Pinnepedia, I have
followed the authors of Bell's British Quadrupeds
(1874), and Mr. Thomas Southwell in his Seals and
Whales of the British Seas (Norwich, 1881). To him
also my thanks are due. The late Mr. G. E. Dobson,
F.R.S., having been the recognised authority for
Chiroptera and Insectivora, I have adopted the
nomenclature of his Catalogue of the Chiroptera
(1878), and of his Monograph of the Insectivora
(1890).
I have to thank Mr. G. A. Boulenger, F.R.S.,
for kind help in naming the Reptilia and Amphibia in
accordance with the methods adopted by the author-
ities of the British Museum.
Essex fishes have been so little investigated by
Essex naturalists that it is certain numerous species
must be omitted from a catalogue compiled, as this to