1122 The American Naturalist. [ December, 
tive tract is reduced to a more slender tubule with scarcely any lumen. 
The main bulk of this region is made up by the seminal receptacles 
two of which are shown as swollen bags full of fresh sperm. There are 
in all four such bags two opening between the 9th and lOth and two 
between the 10th and 11th; as indicated in this figure the openings of 
those bags are tubules that run out through the body wall on the 
dorsal side, not on the median line but some distance right and left. 
Immediately after the region of the sperm receptacles follows the long 
enlargment that reaches from the 12th to 25th rings inclusive. Here the 
digestive tract enlarges as the soft-walled crop in the fifteenth and six- 
teenth rings and then narrows as the gizzard with very thick walls. 
Then from about the eighteenth ring the intestine runs back as a much 
distended tube full-of liquid. The great accumulation of liquid in this 
swollen part of the body between the two constricted areas is a marked 
feature ; the same congested state pertains to the dorsal blood vessel 
which is seen as a very thick tube dorsal to the intestine though in the 
constricted sperm-receptacle region it is reduced to a scarcely observ- 
able and collapsed state. 
What gives this long intermediate region its excessive pilitapis 
and distended appearance at the anterior end, where it seems to over- 
hang the first constriction as seen in fig. 1, is the presence of the huge 
sperm vesicles, or as they are sometimes called testes, which are quite 
full of sperm is various stages of development. They are roughly in- 
dicated in figure 2 as large dorsal bags in the 12th to 16th rings. The 
body wall in this region is thin from distension and the diameter of the 
section is great from the presence of these seminal receptacles, the 
gorged intestine and blood vessel and the accumulated liquid of the 
body cavity. 
The following region, ftom the 26th to 33rd rings is the girdle. It 
has a much thickened glandular wall and is contracted so that the sec- 
tion is small, the intestine, body cavity and blood-vessel all compressed. 
Just posterior to this the section enlarges and the organs take on a 
more normal state of expansion. 
Looking now at the lower worm we find the anterior part essentially 
as in the first case but the next region is even more powerfully con- 
stricted so that these 9th and 10th rings make but a very small show- 
ing in the entire section. 
One of the sperm receptacles is crowded back out of this region into 
the greatly enlarged part that follows. The constriction between the 
two regions has here taken place in the middle of the eleventh ring and 
the pressure has forced the posterior seminal receptacle of the small 
contracted region into the large mass that holds the seminal vesicles. 
