10 Messrs. G. S. Brady and D. Robertson on the 
K. River puis at Woodbridge; L. River Stour at Manning- 
—These rivers are of a character very similar to the river 
Blyth (H), dh of larger dimensions, and, owing totheir course 
through an exceedingly flat country, affected by the tide to a 
Ahi greater distance from the sea. Our gatherings were got 
chiefly from beyond low-water mark; those from the Deben 
at about eight miles from the mouth of the river, the average 
rise of the tide being eight feet ; those from the Stour at about 
iege miles from its mouth, the rise of tide ten feet. 
M. Estuary of the Thames. "The collections from the Thames 
estuary, with the exception of one from the “ Girdler Sand," 
which was procured from a portion of the bank uncovered at 
low water, were obtained by dredging in various parts of the 
estuary between a line joming Margate and the Maplin light- 
house to the eastward, and the Nore to the westward; the 
depths were from two to twelve fathoms ; the ir rise of 
tide at high water over this district is fourteen 
N. er Harbour.—Dredged in from three o" pe fathoms, 
in the harbour, which is the outlet of the river Fowey or 
Losteitbiel Cornwall. Average rise of tide at high water 
thirteen feet. 
Grove II. 
Dykes on the stte d Whittlesea Mere; P.“ Whittlesea 
Dyke.” south of Whittlesea.—These are artificial drainage- 
channels, containing in all Wes a few feet of water, and in 
winter, on the site of the old Whittlesea Mere, often over- 
flowing their banks to a considerable extent; they contain 
abundant aquatic vegetation 
Q. River Nene, between Peterborough and Whittlesea ; 
hese 
the bed of the river, in the Nene at several points over a course 
of about six miles, ‘in the Cam over a very small area near the 
bridge; the distance from the sea is in both cases about thirty 
miles. Notwithstanding the apparently marine character of 
some of the species found in both rivers, it must be remem- 
bered that sea-water finds no access whatever to these locali- 
ties, being entirely shut out by the Denver sluice. And even 
long before the construction of this sluice, it is probable that 
any tidal influence felt at these remote points would be con- 
fined to the driving back of the fresh, rather than the influx 
of salt water. 
Broads of Norfolk and Suffolk may be considered 
as expansions of the various tidal rivers, though situated at 
