660 DR. J. MURIE ON TROCHETA SUBVIRIDIS. [Nov. 14, 
been accidentally swallowed by the Deer while drinking water. My 
attention was further called more fully to ascertain its specific iden- 
tity by its recalling to my mind a notice of a large Leech found in 
the neighbourhood of the Regent’s Park by Mr. Hoffmann, and de- 
scribed by Dr. Gray as being entirely new to the British fauna (see 
Proc. Zool. Soc. 1850, p. 52). 
With the assistance of Dr. Baird at the British Museum, I was 
enabled by comparison to ascertain that this Leech which had been 
found in the Deer was no other than the species commented on by 
Dr. Gray, namely the Trocheta subviridis (Dutroch.) referred to by 
Lamarck in An. sans Vert. vol. v. 2nd edit. p. 523, and also de- 
scribed and figured by De Blainville in the Dict. de Scien. Nat. xlvii. 
246, lviii. 559, Atlas pl. Hirud. fig. 6. Besides, im the monograph 
of the family by M. Moquin-Tandon (p. 309, pl. 4), there is a de- 
tailed account and excellent figures of the external appearance and 
internal anatomy of this species of Leech, where 8 to 12 or 13 cen- 
timétres is given as the size it occasionally reaches, and it is said 
not to be terrestrial, as the author kept one fifteen days in water in 
good health. 
The specimen first found by Mr. Hoffmann near or in the Regent’s 
Park now forms part of the National Collection, and is referred to in 
the ‘ Catalogue of British Non-parasitical Worms,’ 1865, p.45. It 
is there stated to have been 7 inches long when in the fresh 
condition, and now, after being preserved in spirits, as much as 6 
inches in length with a breadth of half an inch. 
The distinctive features of Trocheta subviridis are its great size, its 
large shield-like sucker, the uniformity and narrowness of the rings, 
and the tail-sucker being upon the ventral aspect—with all of which 
our present specimen agrees. It also differs from Hirudo medicinalis 
and Hemopis sanguisuga in the form of its jaws, and in having but 
eight eyes, whereas these have ten. The eyes I could not detect ; 
but, according to M. Tandon, they are occasionally absent or with 
difficulty made out. 
Obtaining this second specimen of a large and rare Leech in the 
same vicinity as the last, it might be looked upon as conclusive that 
it was an animal indigenous to Britain, as Dr. Gray has surmised, had 
I not other facts to detract from this supposition. 
It may either be said that the specimen obtained from the Deer 
found its way thither by being swallowed among the food or water, 
as the animal partook of these in the Gardens; and this fact would 
strengthen the belief of its British habitat ; or, in opposition to this, 
it may be suggested that the ova, or Leech while young, may have 
been taken into the viscera of the Deer in its own native country 
previously to being shipped for England. 
Dr. Baird holds that this last opinion is not tenable, upon the 
grounds that in a voyage of several months it would be sure to die 
itself or pass through the Deer. But in contradiction to his judg- 
ment, Mr. Bartlett relates to me the case of a similar large Leech 
having been obtained from a Yak (Bos grunniens, Lim.) on board 
ship, and before the animal had set foot on these shores. This oc- 
