36 HULL SCIENTIFIC AND FIELD NATURALISTS' CLUB. 



from April to July, and their decease then was due in a great 

 measure to the decay of the Potamogeton. I never observed 

 any new growth, and am inclined to attribute this to the fact 

 that the water was maintained at the April standard of 

 salinity. The natural water shows a wide range of variation, 

 which may be due to the entrance of the Humber water 

 through the primitive clough, and the concentration of the 

 brackish drainage water from the adjoining fields. With 

 regard to the first, some water undoubtedly enters, but never 

 in sufficient quantity to cause any appreciable increase in 

 depth although the drain is only from six to ten feet wide. 

 The samples of water for the following analyses were taken 

 about two-and-a-half miles from the outfall, immediately 

 below the upper limit of Membranipora and Gonothyrcea: — 



Dec. 27, 1901 — Drain partly frozen; depth of water, 1 ft. 



Chlorides = 5*29 grams XaCl per litre. 

 April 1, 1902 — Depth about 1 ft. 



Chlorides = 7 '91 grams XaCl per litre. 

 May 21, 1902 — Depth about 1 ft. 



Chlorides = i8'6 grams XaCl per litre. 

 August 1, 1902 — Depth 6-8 inches. 



Chlorides = 23*8 grams XaCl per litre. 

 Sept, r, 1902 — Depth 6-8 inches. 



Chlorides = 23-5 grams XaCl per litre. 

 The tide of Sept. I, was two feet higher than that of August 1. 



In addition to the species enumerated, P. ventrosa is 

 abundant, Nereis diversicolor attains a larger size than on 

 the Humber foreshore ; Cladophora gracilis (?), which grows 

 in abundance from Skeffling to Spurn, is fairly common on 

 the bridges. 



Former records for the Humber district are Amathilla 

 sabini, "River Humber," Rev. A. M. Norman, "British 

 Amphipoda," Ann. and Mag. Nat. Hist., Ser. 6, vol. iv., p. 

 119; Chiton marginatus and Hydrobia ulvcc, Spurn, W. C. 

 Hey, Naturalist, Nov. 1884, vol. x., p. 92; and "American 

 Shells in the River Humber" {Venus mercenaria), Science 

 Gossip, vol. xxv. p. 115. With regard to the last, Mr. J. R. 

 Hardy informs me that it was, and is still, obtained by the 

 Cleethorpes oyster dredgers, together with the "crow 

 oyster," Crepidula fomicata, another American shell, both 

 having been introduced with oysters. 



Two lists of debris gathered on the tide mark have been 

 published: — " Polyzoa, &c," observed on the occasion of 

 the visit of the Yorkshire Naturalists' Union to Spurn, 

 Sept. 3, 1884 {Nat, Nov. 18S4, vol. x., pp. 92, 93), and 



