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II. Observations on the Hirudo vulgaris. By James Rawlins 
Johnson, M. D. F. L. S. &c. Communicated by the Right 
Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S. 
Read Nov. 14, 1816. 
Strongly impressed with the conviction that every attempt 
to elucidate any part of natural history, will meet with a 
favorable reception, I have ventured to submit to the notice 
of the Royal Society, a few observations relative to the mode 
of propagation, &c. of the Hirudo vulgaris. 
This little animal (PI. IV. Fig. 1, 2.) is found in great 
abundance in rivulets, attached to the under surface of stones, 
and in those situations where it is little exposed to the action of 
the current. It varies as to its length, from an inch to an inch 
and a half, is of a dark brown colour on the back, marked 
with numerous transverse lines, but of nearly one uniform 
colour on the belly, chiefly that of a yellowish green. A 
central line of a black colour passes both on the back and 
belly, from the head to the tail. The ground colour, however, 
differs, hence several varieties have been enumerated. 
From the circumstance of its having eight eyes, which are 
delineated, magnified, in Fig. 4, it has been denominated by 
Linnaeus and others, Hirudo octoculata; but the Hirudo tes- 
sulata presenting an equal number of eyes, we shall give the 
preference to the name under which we find it described in 
Muller, that of Hirudo vulgaris. 
It appears, from ' the statement of an eminent naturalist, 
lately deceased, that this animal possesses the power of 
