HIRU DO. 33 
naciously ; and now the animal protruding from its shell was evidently 
suffering. In this state I left them for several hours, finding the shell 
empty on my return, while the appearance of seven other leeches in the 
vessel plainly indicated that all had shared in the slaughter. 
The margin of all ponds inhabited by the flattened leech and the 
Helix peregra is strewed by myriads of these shells. Before ocular de- 
monstration of the preceding phenomena, I was inclined to ascribe 
the havoc among the latter to some kind of epizooty, such as that which 
is incident to every animal, according to its kind, from the highest to 
the lowest, rather than to a ferocious enemy. But this enemy has as 
little mercy on the Patella fluviatilis (Ancylus), a diminutive limpet, 
though the mode whereby the prey, more defensible, perishes, has not. 
been observed. 
The Helix above named seems to be preferred to all other food ; 
but the leech will sometimes devour mussel and other animal substances. 
This species begins to propagate at an early period. There are 
prolific specimens under half an inch in length when extended. The 
chief season of breeding is March and April, and it continues through- 
out summer. Many are very prolific. Ten of eleven specimens, 
taken promiscuously for observation, produced ova in the course of 
a month. ‘The mode of propagation is very remarkable, nor do I know 
that it has been sufficiently investigated, either by myself, or by other 
naturalists. Six or seven specimens were sent to me from the dis- 
tance of fifty miles, and along with them some of their natural prey. 
What I considered an incipient ovarium was visible in some of the largest 
during the third week of March. Though not uniform in all, this re- 
sembled a regular collection of granules down the middle of the body. 
Where most distinct the under surface of the animal exposed the interior 
on March 20, as in fig. 11. Subsequent observation seemed to indicate 
that the granules occupied pinnate interanea, or were arranged in that 
form. Then they were yellowish, very conspicuous, and in certain speci- 
mens contrasting much with the grey colour of the belly. If truly the 
elements of originating ova or capsules, I was unable to follow their pro- 
gress by slight gradations. 
E 
