82 NATURAL HISTORY OF BRITISH FRESH-WATER LEECHES.
flat and of a brownish colour. They are deposited on leaves and
stems of plants, sticks, stones, etc. The mode of fertilization
and the manner in which the cocoon is fixed are described on
p.p. 68-69. Breeding takes place from May to October. Rawlins
Johnson (31) states that one individual deposited 12 cocoons
during a period of 21 days. Each cocoon contains from 6-12
ova, and the period of incubation extends 30 to 70 days according
to the state of the weather.
Distribution.—As this species is so often confused with H.
atomaria, it is impossible to know to which species the records
belong. It is very widely distributed, however. The writer
has taken specimens from the following localities:—Epping
Forest, near Abridge in stagnant pond, Richmond Park, Chalfont
St. Peters, Staines.
Herpobdella atomaria Carena (Nephelis vulgaris). Plate
VIT, Figs. 7 and 8.
Description.—Very much like H. octoculata, but lighter in colour and
with yellowish spots on the dorsal surface. The first ring of each somite
is much lighter in colour than the others. In this species the genital
pores are separated by three rings (Plate VII., Fig. 8). Somite V is usually
biannulate.
Habits.—Similar to those of H. octoculata.
Distribution.—Common. The writer has taken examples
at Chigwell Row ; Epping Forest ; R. Roding, near Abridge ;
Richmond Park ; Staines ; Totteridge ; R. Chess ; R. Wharf,
Grassington, Yorks.
Trocheta subviridis Dutrochet. Dutrochet's Leech. Plate
VIT, Fig. 14.
Description.—Body elongated, vermiform with well marked sucker at
the posterior end. Dorsal surface dark brownish green, with two dark-
brown longitudinal bands. Ventral surface of a lighter hue. A distinct
clitellum is often present. There are normally eight eyes, 4 in the second
ring and two lateral pairs in the fifth ring. The anus opens between the
third and fourth ring, reckoning from the posterior disc (cf. Haemopis
sanguisuga). Length at rest 80-100 mm. ; 200-215 mm., when extended.
Width 7-15 mm.
Habits.—Lives in streams contaminated with sewage, and on
land in gardens, on lawns, paths or under boxes. It feeds upon
earthworms, which are swallowed whole. The cocoons are
elliptical, dark brown and are attached to foreign bodies. They
measure from 9-14 mm. in length and 6-8 mm. in width.