DEVELOPMENT OF ACANTHODRILUS MULTIPORUS. 501 
while p is a worm ready to leave the cocoon, and showing the 
principal blood-vessels. 
Unfortunately I have very little material belonging to the 
younger stages; I have only one specimen of stage a, and 
three or four of 8. But considering the length of time which 
elapsed between the collecting of the cocoons and their arrival 
at the Zoological Gardens, I may regard myself as extremely 
lucky in having such a comparatively large series of the 
younger stages. 
Besides the embryos in the cocoons, there were about half 
a dozen young worms which had been hatched during the 
voyage. 
It seems evident, therefore, that the development of this 
species may take a considerable time. 
The case arrived at the Zoological Gardens on August 11th; 
it was packed for transmission at latest on June 23rd; a period 
of seven weeks therefore intervened. 
The rate of development also must differ considerably, as 
Wilson (15) has pointed out in the case of Lumbricus; but 
the shortest time, so far as I can judge by the evidence 
afforded by the specimens sent me, can hardly be less than 
five or six weeks. This is about double the period which 
Wilson found in two species of Lumbricus. It was always 
possible to detect an “addled” cocoon by observing whether it 
did or did not float in water: healthy cocoons with living em- 
bryos inside them always sank to the bottom; if the cocoons 
floated on the surface of the water it was a sign that the 
embryo was dead. 
I have oceasionally met with Nematodes in the interior of 
earthworms’ cocoons, as have other observers. In two co- 
coons of Acanthodrilus multiporus with partially decayed 
contents I found not Nematodes, as I at first thought, but 
several examples of an Enchytreid not yet identified: a 
curious circumstance was that the majority of these small 
Annelids were dead,—infected, I suppose, by the decaying 
matter round them. I saw another example on the moss, 
which is probably the habitat of the species. This family of 
