143 
generation of the lamprey , the conger eel , &c. 
All these circumstances are most distinctly illustrated by 
the drawings. 
On the Organs of Generation of the Earth Worm. 
It is now six years since Mr. Bauer very kindly offered 
me his assistance in this enquiry. Our joint labours have 
been frequently interrupted by subjects of more interest ; we 
have, however, at last completed this investigation, and so 
much is represented in the drawings, that little is left for 
verbal description. 
The mode of copulation resembles that of the leech more 
than of the snail ; but when the animals are separated there 
is this curious difference : in the leech, an animal much 
smaller than the earth worm, there remains protruded a penis 
an inch long ; a little lower down on the belly is the orifice 
leading to the uterus or ovarium ; so that the first impression 
I received was, that the length of the penis enabled the leech 
to copulate with itself, till my friend, Dr. Johnson, laid be- 
fore the Society an account of its copulation with another 
individual, which he had seen. 
When two worms in copulation are forced asunder, there 
is upon neither of them any appearance of penis or vagina. 
There is a pair of longitudinal slits or suckers a little way 
from the head on each side of the belly of both worms ; 
lower down a pair of hooks corresponding to each pair of 
suckers. 
Their mode of copulation is as follows : 
Two worms come out of two neighbouring holes a few 
inches apart, so that there is sufficient space for them to copu- 
late, and for one-third of the length of each worm to remain 
