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Proceedings of the Royal Society 
certain species of earthworm, characterised by the fact that the 
clitellum occupies 10 segments ending with the 38th, that the seta? 
of each pair are rather widely separated, the nephridial pores being 
placed in front of and a little to the outside of the outermost of the 
two ventral setae, has a certain internal structure, the most marked 
characters being (1) the presence of four distinct vesiculae seminales, 
(2) the presence of seven distinct pairs of spermathecse situated in 
segments 5-11 inclusive. It is only by such comparisons of 
internal and external structure that the limits of genera and species 
can be determined, and the at present confused synonymy of 
Lumbricus reduced to anything like order. 
6. On the Physical Conditions of Rivers entering a Tidal 
Sea ; from Observations on the Spey. By Hugh 
Robert Mill, B.Sc., and T. Morton Ritchie, B.Sc. 
(Plates XIII., XIV., XV.) 
In connection with the observations carried on by one of us on 
the salinity and temperature of estuaries,* it seemed desirable to 
examine the condition of the water near the mouth of a river 
flowing directly into the sea. For this purpose it was necessary to 
select a stream of considerable volume and free from pollution. 
As the Spey appeared to be the most suitable river, we spent the 
month of August at Garmouth, a small town close to the old port 
of Kingston, on the west side of the river mouth. "We have to 
express our thanks to Mr Balmer, Commissioner at Fochabers to the 
Duke of Richmond and Gordon, for much kindly interest in our 
work, and for affording us the use of the facilities presented by the 
salmon-fishing station of Tugnet on the east bank of the river. 
The Spey is the most rapid river in Scotland, and next in size to 
the Tay. It is 120 miles long, including windings, and drains an 
area of 1245 square miles. It flows in a northerly direction into the 
Moray Firth, which is not an estuary in any sense of the word, but 
* Mill, “ On the Salinity of the Water in the Firth of Forth,” Proc. Roy. Soc. 
Edin ., xiii. pp. 29-64; Abstract in Nature, xxxi. p. 541; ‘ ‘ On the Temperature 
of the Water in the Firth of Forth, ” Proc. Roy. Soc. Edin., xiii. pp. 157-167 ; 
“On the Salinity of the Estuary of the Tay and of St Andrews Bay,” ibid., pp. 
347-350 ; “On the Physical Conditions of Water in Estuaries,” Brit. Ass. 
Rep., 1885, and Scottish Geographical Magazine, ii. pp. 20-26. 
