MB. R. GURNEY ON FRESH- AND BRACKISH-WATER CRUSTACEA. 651 
Idotea viridis (Slabber). I am not quite satisfied that my iden- 
tification of this species is correct, but at all events 
I cannot make it agree with any other known to me. 
It occurs in Ploughman’s Ham near Lake Lothing, 
and brackish ponds at Cley. 
Amphipoda. 
Gammarus pulex (De Geer). Very rare in my experience. The 
only records I have are : Sutton Broad, Barton 
Broad, Harford Bridges, Sprowston and in the 
Black water river. It seems that it is confined to 
absolutely fresh water, and is probably common 
enough in the higher reaches of the rivers. 
„ dueheni, Lilljeborg. This species takes the place of 
G. index in the Broads district wherever the water 
shows traces of salt. It is abundant in the Hickling 
region. Some specimens that 1 have seen appear to 
show more or less of a transition to G. ]mlex, the 
uropods particularly being rather less spinous than 
the type. 
,, locust a (Linn.). Though properly a marine species 
I have one record of G. locusta from the Yare at 
Reedham in a collection of fresh-water species. 
Nipiiargus puteaxus, Koch. Recorded by Dr. S. F. Harruer 
from a well at Cringleford (1899). 
Corophium grossipes (Fabr.). I have taken this species at 
various places in the Yare and Bure, and have 
found it particularly abundant on piles in the Bure 
near the Muckfleet. 
„ crassicorxe, Bruzel. This species is included on the 
authority of Mr. Stebbing,* to whom specimens 
were sent by Mr. R. Scherren. The latter states 
that they were taken in the Thurne “ not far from 
the Broad which the courts recently declared was 
not tidal.” Its presence there can be more readily 
explained by the fact that salt water Hows down 
from Horsey, than by the assumption that salt tides 
flow normally up the Thurne river. 
* ‘ Victoria County History,’ Norfolk, vol. i. p. 192. 
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