NOTE ON ZYGODON FORSTERI MITT. 85 
44. WHITEHEAD, H. (1911). : Dutrochet's Land Leech in Essex. 
Essex Naturalist , XVI, pp. 219-221. 
45. WHITMAN, C. O. (1898) : Animal Behaviour. Biol. Lect. Marine 
Biol. Lab. Woods Holl. Mass. (See also Distant. Zoologist (4) 
V. (1901) p. 235.) 
(A full bibliography of the subject is given at the end ot Harding’s paper.) 
Fig 1. 
,, 2. 
>» 3 * 
»> 4* 
» 5- 
Fig. 7. 
8 . 
>» 9* 
tt 
,, 11. 
„ 12. 
„ 13- 
,, 14- 
E XPLA NA TION OF PL A TES. 
PLATE VI. 
Piscicola geometra. 
Protoclepsis tessellata. 
Ilemiclepsis marginata. 
Glossosiphonia heteroclita. 
G. complanata. 
Helobdella stagnalis 
PLATE VII. 
Herpobdella atoinaria. 
H. atomaria , showing positions of genital pores. 
H. octoculuta , showing positions of genital pores. 
Hcemopis sanguisug.i. 
Hirudo medicinal is . 
H. medicinalis , details of pattern on dorsal surface. 
H. medicinalis , details of pattern on ventral surface. 
(Figs. 11 -13 are drawings from a specimen taken in the New Forest). 
Troche (a subviridis . 
(Diawn from a specimen taken at Theydon.) 
NOTE ON ZYGODON FORSTERI MITT. 
By PERCY THOMPSON. 
T HE recent re-discovery by my wife of Zygodon forsteri 
Mitt., one of our rarest and most local British mosses, in or 
close to its first recorded habitat in Epping Forest,has been con¬ 
sidered by the Editor of sufficient interest to warrant the following 
note on the few occurrences of this moss hitherto recorded. The 
moss was first noticed by T. F. Forster at some time prior to 1794, 
on a felled tree-trunk in a timber-yard at Chapel End, Waltham¬ 
stow, which trunk had most probably come from the 
neighbouring forest. 
For many years no second occurrence of Zygodon forsteri was 
noted, save a dubious record from Sussex, by E. Jenner, which 
has never been verified. 
In 1879 Miss I. Gifford found a specimen in a field at Minehead, 
