MARINE ZOOLOGY 



which must vary much with the season. Passing down the river to 

 beyond Shoeburyness there is the large flat tract of the Maplin Sands, 

 in some parts 3! miles wide at low water. I have examined this 

 imperfectly off Havengore and at the east end of Foulness. In the 

 Swin, off the Maplin Sands, the water is deeper than anywhere else 

 along the coast of Essex, but yet its maximum depth is only 1 3 fathoms, 

 maintained by the strong tidal currents. Passing westwards along the 

 northern side of Foulness we have the estuaries of the Crouch and 

 Roche, as well as sundry channels and creeks, all having muddy shores, 

 but no extensive flat tracts left dry at low water. In these estuaries and 

 creeks oyster culture is of such importance that hundreds of men are 

 employed, and some of the river beds are worth one hundred times as 

 much as the adjoining meadow land. I am best acquainted with the 

 Crouch, having remained in it off Burnham many times for weeks. 

 When there in summer I have found the low water more salt than the 

 high water, which is an unusual thing in an estuary ; and the water at 

 Battle Bridge, 12 miles from the mouth, more salt than the North Sea, 

 no doubt owing to small rainfall and great evaporation. North of 

 Foulness to the estuary of the Blackwater is a sandy tract left dry at 

 low water for a width of a mile, which I have never examined for 

 marine animals. In the estuary of the Blackwater, often called ' Pont,' 

 I have examined the shores near Bradwell, and have dredged off an island 

 called Osea. Between the Blackwater and the Colne are sundry creeks 

 near West Mersea, and a tract of more or less sandy mud, left dry at 

 low water for a width of ^ mile, the east end of which I have examined 

 to some extent. I have lived in the estuary of the Colne for weeks at 

 a time almost every year for more than twenty years, and have examined 

 the shores and creeks in every direction, and dredged and trawled in the 

 open water off Mersea. On the east side of the Colne, both above and 

 below Brightlingsea, there is good ground for collecting at low water from 

 a boat or in long waterproof boots. Between the Colne and Walton-on- 

 Naze is a long extent of coast with narrow sands, which I have never 

 examined. The open water off this, in the Wallet, is seldom more than 

 6 fathoms deep, which is no more than in some of the estuaries. On 

 one occasion I dredged in this near the Gunfleet Bank, but in many 

 places the ground is too full of large stones for dredging purposes. The 

 creeks on the east side of Walton-on-Naze are very good collecting 

 ground. In 1889 I remained some time in what is marked on the 

 charts as ' Walton Channel,' but I know nothing of its present condition, 

 since the sewage discharge from Walton was so objectionable that I have 

 not gone there again. But for this it would be the best place on the 

 coast for collecting, since there is no oyster culture and no disturbance 

 by steamboats. East of the Naze is a tract of coast which I have never 

 examined, except near Harwich. Both outside and inside the harbour 

 is or was excellent collecting ground in fine calm weather, but when it 

 is windy little or nothing can be done. Passing up the Stour are vast 

 tracts of mud, covered with Zostera marina, which are left dry at low 



