482 FOOT. [Vou. XIV. 
ments of the worms, and so elastic that after pressure it 
springs back to its original shape. At this stage, and when 
encasing the cocoon (Figs. 3 and 4), its form is so tube-like 
that I shall designate it the slime-tube. It can be injected 
from both ends ; in some cases the colored fluid will flow 
freely through the entire tube, and again it will fill only one- 
half, and the other half can be injected with another color. 
I am inclined to think this semi-independence of the two 
tubes is the usual condition; for after deposition each 
cocoon is encased by its own tube (Figs. 3 and 4). There 
is, however, an intimate connection between the two; for 
when the copulating worms are disturbed, in many cases one 
worm will escape first, leaving both tubes around the other 
worm. When the slime-tube is torn, as seen in Fig. 2, the 
torn portion can be peeled off from the rest as though it were 
a separate layer. The entire layer can be pulled off back- 
wards with a pair of forceps, — can be turned inside out without 
tearing. 
Within the slime-tube flows the seminal fluid, containing 
free spermatozoa and spermatophores. I designate as sperma- 
tophores the branched bundles of spermatozoa which are aggre- 
gated at the distal ends of the slime-tube (text Fig. 2). Dur- 
ing the early stages of the formation of the cocoon, these com- 
pletely cover the dorsal surface and sides of segments 9 to 11 of 
each worm and are packed between the two worms at this 
region. The contents of a partly formed cocoon, when shaken 
in water, break up into several of these formations, often as 
many as six, many of them as large as that represented in 
text Fig. 2. I have never found any eggs in the slime-tube 
before the cocoons were partly formed, this fact indicating 
that the eggs are deposited towards the end of copulation. 
As these worms copulate at a greater or less distance beneath 
the surface of the earth, at least one function of the slime- 
tube must be to protect and confine the seminal fluid and 
spermatophores. If this interpretation be correct, we should 
find this slime-tube encasing all freshly deposited cocoons of 
worms which copulate beneath the surface of the earth. I 
have found this to be the case for several species, and 
