March 10, 1870] 
NATURE 
483 
in a letter dated February 18, informs me ‘‘I have received 
thirteen Little Gulls, shot on the Bridlington coast during the 
last fortnight, seven adults and six immature.” And, in a recent 
communication, ‘* There have been twenty-nine Little Gulls shot 
in all, nineteen old and ten young birds.” 
Ihave a photograph of an adult bird in breeding plumage, 
with the black head, shot at Flamborough on July 13, 1868. 
Great Cotes, Ulceby, Feb. 25 JOHN CORDEAUX 
THE MICROSCOPIC FAUNA OF THE ENGLISH 
FEN DISTRICT 
ee results of some recent researches amongst the 
Entomostraca of the rivers and “broads” of Nor- 
folk and the adjacent counties have proved so interesting 
that a brief résvmé of the subject will probably not be 
unacceptable to the readers of NATURE. 
Myattention was first directed to the district in the follow- 
ing manner :—My friend, Mr. E. C. Davison, a gentleman 
attached to the staff of H.M.S. Porcupine, has for several 
years interested himself very kindly, during the annual 
cruises of the vessel, in collecting for me such Entomos- 
traca and other Microzoa as came in his way. Amongst 
the gatherings which thus came into my hands were two 
samples of sand from the Dutch rivers Maas and Scheldt, 
some similar dredgings from the English river Ouse 
(Norfolk), and one from Oulton Broad in Suffolk. The 
Dutch gatherings had been in my hands for several years, 
and their ostracoda described in the “ Annals and Maga- 
zine of Natural History,” before I received those from the 
English localities. An examination of these at once re- 
vealed a remarkable similarity between the inhabitants of 
all the localities—several species, up to that time unknown 
in Britain, being recognised as identical with some of 
those taken in Holland. This interesting observation 
induced me, in company with Mr. D. Robertson, of Glas- 
gow, to visit the Fen district with a view of more tho- 
roughly investigating its microscopic fauna—an inquiry 
which has resulted in very much strengthening our 
original view as to its close relationship with that of 
Holland, and seeming, moreover, to indicate that we 
have in the English fens a very remarkable group of 
Ostracoda and Foraminifera marked out by a hard and 
fast line, and forming a district fauna quite unparalleled 
in its isolation, as regards the surrounding British 
species. 
The fact of a partial relationship between the fauna of 
the Fen counties, or East Anglian district, as we may con- 
veniently call it, and that of North-Western Europe is 
not new ; and the best account of the matter that I know 
of may be found in an interesting article on “ The Fens,” 
by the Rev. Canon Kingsley, in Good Words for 1867. 
The facts which most prominently indicate this relation- 
ship are the presence of various fishes of the family 
Cyprinidaee—roach, dace, &c., which attain their highest 
development in the rivers and lakes of Sweden,—of the 
“bearded tit,” now however probably nearly extinct, and 
of the remains of the fresh-water tortoise, E71ys lutaria, 
now an inhabitant only of Central and Eastern Europe, 
and whose presence in England can scarcely be accounted 
for except on the supposition of a free river communica- 
tion between our island and the Continent during a by- 
gone geological epoch. That the Straits of Dover were, 
indeed, not very long ago (geologically speaking) bridged 
over by dry land, and that at that time the rivers of North- 
Western Europe emptied themselves into one great 
estuary situated between us and the Scandinavian penin- 
sula are well-established facts; and it is as giving 
additional confirmation to this belief by exhibiting perhaps 
more fully than has previously been done the close rela- 
tionship of the fluvial faunas of East Anglia and Holland, 
that our present observations claim their chief interest. 
For it is evident that two faunas, possessing in common, 
even according to our present imperfect knowledge, a 
considerable number of species at once very peculiar in 
character, apparently very restricted in their distribution, 
and separated at the present time by a wide expanse of 
sea, must have sprung originally from one common centre, 
and can scarcely have been finally separated for any 
great length of time. The fishes to which we have re- 
ferred have indeed spread, either through natural or 
artificial agencies, from the eastern rivers to other parts 
of England and even to Ireland. But this crustacean 
fauna seems to be rigidly confined to the Fen district of 
Norfolk and Suffolk on the western side of the German 
Ocean, and to the rivers of Holland on the eastern side. 
We make this assertion with some reserve, because much 
yet remains to be done in the examination of aquatic 
microzoa everywhere, and it is just possible that some of 
those species which we take to be peculiar to the Fen 
fauna may turn up elsewhere. But we have ourselves 
examined dredgings from many English rivers, especially 
on the east coast, and have explored in the search 
for Entomostraca (though without dredging), the lake 
districts of England and Southern Scotland, without 
ever meeting with any of them. In no part of the con- 
tinent of Europe have the Entomostraca received so 
much attention as in Scandinavia, where, if anywhere, we 
should expect a similar fauna to be found. But neither 
Miiller, Lilljeborg, nor Sars appears to have met with 
such. Nor does M. Felix Plateau’s recent memoir on 
the ‘“‘Fresh-water Crustacea of Belgium” mention any 
similar species, though we cannot help thinking that had 
the dredge been used there, the result would have been 
different. 
Out of about 180 known species of British Ostracoda, 
eighty may be frequently met with in river estuaries or in 
marine situations where much fresh water habitually 
mingles with the salt. Of these, thirteen may be con- 
sidered as coming down to the debatable ground from the 
fresh-water side and fifty-six from the sea ; the remaining 
eleven haunt brackish water almost exclusively, so much 
so, indeed, that were they found to any large extent in a 
fossiliferous deposit, we should have no hesitation in saying 
that it was produced under brackish conditions. 
Of about 100 species and varieties found in the Fen 
district and its outlets, sixty-eight may be looked upon 
as usual inhabitants of either marine or estuarine situa- 
tions. These are met with chiefly in the river outlets, and 
being, doubtless, derived from the sea may be left out of 
sight in any consideration of the fauna of the Fens. 
Again, nineteen are widely-distributed fresh-water species, 
of which little need be said except that those of the genus 
Candona, especially C. compressa, albicans, and Jdactea, 
seem here to attain a finer development and to exist in 
much greater abundance than in any other district. 
In connection with this it is curious to observe that the 
genus occupies an intermediate position between the 
crawling, non-natatory marine Cytheridz and the freely 
swimming fresh-water Cyprides. Twelve (?) species, mostly 
undescribed, seem to be entirely or almost entirely con- 
fined to the fens of England and the corresponding dis- 
tricts of Holland, for we regard their appearance in 
dredgings from the estuaries of the Scheldt and Meuse 
as evidence, not of their /2vz#g in those situations, but of 
their probable abundant existence nearer the water-head. 
Dead shells of the same species are met with in a similar 
manner in the river outlets of Norfolk, such as the Ouse 
and Breydon water, their real habitat being the fresh- 
water “broads” and the dykes and rivers as high up as, 
and very probably higher than, Peterborough and Ely. 
The peculiar species of the district are the following :— 
Goniocypris mitra, Brady and Robertson; ALetacypris 
cordata, B.and R.; Cypres fretensis, B. and R.; Cypridopsts 
Newtont, B. and R.; Candona Kingsleiz, B. and R.; C. hya- 
lina, B.and R.; Cythere fuscata, Brady ; Limnicythere mon- 
strifica, Norman; L. Sancti Patricit, B. and R.; Polycheles 
Stevensont, B,and R.; with some few other species of which 
