76 NATURAL HISTORY OF BRITISH FRESH-WATER LEECHES. 
species of fresh-water fishes, and may remain on its host for 
some days. It is fairly common in trout fisheries. 
The cocoons are deposited on water plants, and each cocoon 
contains one egg. According to Brightwell (9) the cocoons 
are laid within 24 hours of copulation and the young are hatched 
30 days after deposition of cocoon. 
Distribution. —So far this species has not been found in Essex, 
but it probably occurs. 
Britain :—R. Thames, Bourne End (Blair) ; R. Wensum 
(Brightwell, 9) ; Eckington Canal (Evans, 15). 
Ireland :— N. Ireland; R. Dodder, Co. Dublin (Scharff, 39). 
Foreign :—Widely distributed in Europe. 
Protoclepsis tessellata, O.F.M. ( Clepsine tesselata). The 
Chequered Leech. Plate VI., Fig. 2. 
Description. —Body flattened, translucent. Large specimens have a 
brownish tinge, smaller ones are greyish and sprinkled with fine black 
dots. When extended the body tapers slightly towards the anterior 
end, but when contracted it is ovoid in outline. Length of adult about 
25mm. The body has on its dorsal surface six well marked longitudinal 
rows of greenish grey dots, while smaller dots are distributed irregularly. 
The head has four pairs of eyes which are placed in two parallel rows. 
Complete somite consists of three rings. The genital openings are 
separated by four rings. 
Habits. —Small specimens taken by the writer were very 
active, but a very large one measuring 30 mm. long and 13 mm. 
across when contracted and 55 mm. long when stretched was 
very sluggish in its habits. It is found on weeds and under 
stones. It drags the body along without raising it from the 
ground, and is unable to swim. Accounts of the egg-laying 
habits of this species differ considerably. The large specimen 
mentioned above deposited in June 36 eggs in 3 cocoons on 
the bottom of the tank and then brooded over them. The 
young when hatched attach themselves to the parents’ body 
[ante p. 69). Houghton and O. F. Muller state the number of 
young as 200 and 300 respectively, but it does not necessarily 
follow that all the young attached to the body of an adult are 
offspring of that individual. 7 This species is parasitic upon 
ducks and other water-birds. Examples have been taken from 
wigeon, teal, long-tailed duck and domestic duck, the favourite 
7 Mr. Blair furnishes me with the following note. “ A specimen of this species laid 250 eggs 
in three cocoons and hatched them all, but had to reject 100 as there was not room for them 
to attach themselves to the parent. They hatched about 20 days after deposition.” 
