654 MR. R. GURNEY ON FRESH- AND BRACKISH-WATER CRUSTACEA. 
Neatishead had such an origin. This part of the Broad resembles 
very closely the “ pulks” of Wroxham, being more or less shallow, 
and having a bottom of soft yellow mud with little vegetation. 
This type of mud does not occur, as far as 1 know, in the Northern 
half of Barton or elsewhere in the group. This South-western 
arm of Barton is also enclosed by more or less high wooded ground. 
The fauna shows somewhat of a transition towards the Broads 
of the Bure in the relative abundance of certain species such 
as Ilyocryptus agilis, and in the presence of Nitocra hibernica, 
which does not occur in Sutton ; Daphnia cucullata is also fairly 
frequently met with as a straggler from the river. In one respect 
this group has some resemblance to the preceding one ; both groups 
are characterised by the presence of large beds of Chara, and 
I do not know of any other Broads in which the Characece attain 
to anything approaching the luxuriance which they show in these 
two groups. 
Calthorpe Broad belongs geographically to the Hickling region, 
but it is quite distinct from the Broads of that region faunistically. 
It is a small Broad of about five acres, isolated, except for indirect 
connection by means of ditches with the Waxham Cut leading to 
Horsey Mere. During the past year the Broad was much grown 
up with weeds, and the Crustacean fauna was poor. The total 
absence of Bosmina longirostris and Diaphanosoma brachyurum 
is remarkable, since in 1900 both species were abundant, and 
in 1901 the former was still present in considerable numbers. 
Possibly the great growth of weed was the cause of their 
disappearance. 
Of the Broads of the Bure, I have not been able to investigate 
Hoveton, but the others seem to be all more or less alike in all 
characters. South Walsham and Ran worth, however, may be 
conveniently separated from Wroxham and Salhouse, in that they 
are within the reach of the “ brackish ” species which extend at 
the limit of their range into fresh water. Thus Tackidius littoralis 
and Eurytemora affims have been found occasionally in both. 
All these Broads differ from those of the preceding groups in 
respect of their wooded surroundings, and in having, as a rule, 
comparatively little weed. In particular the Cliaracece are, if not 
absent entirely, at least never seen in any luxuriance. 
Ormesby, Rollesby, and Filby Broads form an isolated group, 
