320 
THE OCCURRENCE OF A LEECH (TROCHETA 
SUBVIRIDIS) IN AN ALLOTMENT. 
By R. A. HARPER GRAY, M.A., B.Sc. (Age.), M.Sc., 
Adviser in Agricultural Zoology, Armstrong College , Newcastle upon Tyne. 
In April of this year (1922) a specimen was sent to the Agricultural Depart¬ 
ment, Armstrong College, by Mr S. Giles of South Shields, along with a note 
explaining that it had been found “down in the first spit of the soil” in one 
of a group of allotments there. It was obviously a specimen of a leech, but 
the specimen was submitted later, to Mr John Ritchie, the Museum, Perth, 
who kindly identified the species as Trocheta subviridis, and who mentioned 
that “this gives so far as I am aware, a more northern habitat than hitherto 
recorded. See Parasitology, vol. hi, p. 182.” 
Apart from the fact that this particular species has been recorded in 
England only at rare intervals, it is interesting to record the occurrence of a 
form on land that has been cultivated for several years, seeing that the 
Hirudinea are associated usuallv with a water habitat. 
t j 
A description of Trocheta subviridis is given by Harding in his paper on 
British Leeches 1 , to which Mr Ritchie refers, and it appears that up to 1910 
it had not been recorded from Scotland or Ireland, and in England the first 
reliable record (1850) refers to the finding of a single specimen in Regent’s 
Park. Subsequently it was found “at no place very remote from London.” 
More recently, however, in 1909, specimens were found at the Withington 
Sewage Works, near Manchester, where they were occurring in sewage effluent 
channels, and feeding upon earthworms there. 
As is often the case with isolated occurrences of a species, it is somewhat 
difficult to account for the presence of Trocheta subviridis in the South Shields 
allotment. The allotments lie on a clay bed, and in the one containing the 
leech, the clay occurs, in places, a few inches below the surface. As there 
is no drainage system, the land has been trenched to the depth of one and a half 
spits, and a well sunk in the clay in one corner, into which an endeavour is 
made to collect water in winter. Notwithstanding this, however, it appears 
that the land tends to become waterlogged during winter, but in April the 
soil was quite workable, and the leech was found at a considerable distance 
from the well. 
1 “A Revision of the British Leeches,” by W. A. Harding, M.A., F.L.S. (1910). Parasitology, 
in. 130. 
