Ostracoda and Foraminifera of Tidal Rivers. 5 
character. Their introduction along the river-channels at the 
present time can scarcely be thought possible; moreover there 
are two facts which strongly oppose such an i idea. In the first 
place, we find in the dykes about Whittlesea several Forami- 
nifera and Ostracoda, of marine character, which do not occur 
in our gatherings from the closely adjacent river Nene*, and 
which would therefore gas to be the relics of a previous 
fauna; secon some the species found commonly in 
the most inland waters of the East-Anglian district are un- 
known anywhere else, and certainly cannot have been intro- 
duced from the sea. Judging from analogy, we may, indeed, 
say with tolerable certainty that some of them are unfitted for 
a marine habitat, and, at any rate, are not now to be found there. 
The Ostracoda specially characteristic of the East-An lian 
district, and here, (except "Oythere Juscata) first described, are 
Goniocypris mitra, nov. gen. & sp. 
Polycheles Stevensoni, nov. gen. § sp. 
Metacypris cordata, nov. gen. § sp. 
Cythere fuscata, Brady. 
More or less frequent also throughout the district, but of 
doubtful significance, because probably spreading beyond its 
limits, and being also less pronounced in external character, are 
Cypris fretensis, nov. sp. Limnicythere Sancti- Patricii, 
Cypridopsis Newton, nov, Sp. D. $ R. 
Candona Kingsleii, nor sp. Cytheridea torosa (Jones) (torose 
Candona niasa . Sp. form). 
eM These species are Metacypris o Cypris fre- 
tensis, Cythere dues nd Polycheles Stevensoni. It is not 
to; and it is interesting and important to fin a further con- 
pee of this relationship in the mia inhabitants of 
* dredgings in the river Nene made a ral points 
course np nt six miles between "Peterborough sub W these, and 
must have included ever San A t characteristic E the des 
ricer sa that, though . aem eran en ery abundan Whittl 
ea dykes, scarcely any iniae in the river Ñene. 
