MUSEUM OF COMPARATIVE ZOOLOGY. 175 
female.! Furthermore, in the entire collection which Professor Verrill 
kindly placed at my disposal there was only one female, that one being 
found coiled up in a mass of twenty specimens. 
Biirger (p. 647) describes one form which differs materially in struc- 
ture from all others studied by him; he was inclined to regard it as a 
female. He found a sac with flattened walls hanging from the dorsal 
line. The description and figures given by him resemble strongly an 
immature testis, — certainly it cannot be an empty ovary. But the ter- 
mination which he describes for it is so extraordinary that one must 
doubt the normal nature of the specimen or the accuracy of the obser- 
vations. Certainly neither in male nor female does one find anything 
like the tube and cells which he describes as lying on the ventral cord, 
except the esophagus. It is impossible, however, that he has mistaken 
the anterior for the posterior end of the worm, because he mentions the 
head of this specimen. There are certain points in his description of 
this individual, especially the lack of an anal ganglion, which recall the 
female, yet in view of the many problematic points which cannot be 
referred to either sex, I am of the opinion that this must have been a 
very abnormal specimen. I shall give a description of the sexual organs 
of the female without any further reference to his work, describing only 
those conditions which I believe to be normal. 
The three females obtained present three stages in the growth of the 
egg, but unfortunately all are too far advanced to give any clue as to 
the place or method of origin of the egg cells. In the first stage the 
body cavity is already half filled with well developed eggs, and no trace 
of ovaries or of the walls confining the ova is present, but the ova 
seem to lie free in the body cavity. Each egg (Plate IV. Fig. 60) has 
a firm outer membrane, highly granular protoplasmic contents, and a 
large irregular nucleus, which has a very thin nuclear membrane and 
is strikingly poor in chromatic substance. Between and around the eggs 
one finds a granuiar substance, and more rarely small nuclei. 
In the next older stage the body cavity is more nearly filled, and the 
eggs are very similar except that the nucleus is smaller and more deeply 
stained. One finds also around each egg an external covering of minute 
quadratic blocks, which seem to be easily separable from the egg and 
from one another. 
The oldest stage observed differs from that just described in some 
1] should not neglect to mention that a female with protruding egg mass 
(see Fig. 10) would correspond generally to this description; but such a state 
would hardly be available for identification. 
