FISH ENTOZOA FROM YELLOWSTONE PARK. Si | 
of minute, short filaments felted together (Fig. 21, s). These, when 
isolated, appear as slender filaments with a black speck at one end. 
They are presumably spermatozoa. I was not able to demonstrate 
any communication between the testes and the vas deferens from my 
sections. The wall of the cirrus-bulb is thick and well supplied with 
circular muscular fibers, and within there are numerous retractile 
muscular fibers. The cirrus was retracted in all the specimens. The 
aperture of the cirrus, as seen in section through the retracted organ, is 
quite irregular, with puckered walls and its longer axis transverse to the 
long axis of the body (Fig. 19, ¢ 7). 
The germ gland or ovary lies transversely across the body about 
midway between the genital aperture and the posterior end (Figs. 
13, 14, 15, 7). It is wsingle organ, though comprising two marginal 
lobes with a narrower connecting part. The latter disappears in 
specimens which have become replete with ripe ova, while the marginal 
lobes still remain (Fig. 14, g). In such cases there appear to be two 
ovaries. In Fig. 13 there appear to be two ovaries. The sketch was 
made from a section which passes on the dorsal side of the part which 
connects the marginal lobes. It is thus seen that the marginal portions 
of the ovary extend farther toward the dorsal side than the part which 
connects them. The ovaries are made up of nucleated cells closely 
and uniformly packed together. They do not lie in clusters or nests like 
the granular nuclei of the testes and the vitelline glands. In the older 
specimens, however, the ovary appears to be broken up into lobular 
portions (Fig. 14, 9). The ovary as a whole lies nearest the ventral face 
of the body. 
The vitellaria (Figs. 13, 14,15, vg) in the younger specimens are seen 
to consist of two marginal glands which connect with a posterior gland 
lying behind the ovary. In the adult specimens this organ may be 
divided into at least three distinct glands, one posterior and two mar- 
ginal. The vitellarian gland differs from the ovary in being lobulated, 
and in, the lobules there are numerous clusters of granules, appearing 
in section as cireles or oval nests of nuclei. This organ is well de- 
veloped along each margin in the vicinity of the cirrus bulb, extending 
forward of the cirrus bulb for a short distance and overlapping the 
testes. I observed small ducts leading from the marginal glands, but 
found nothing corresponding to the conspicuous marginal ducts noticed 
by Van Beneden in his account of the anatomy of the related genus 
Caryophylleus. 
The ducts from the vitellaria were in some cases crowded with small 
‘ globular masses, which apparently originate from the disintegration of 
the nests of nuclei in the vitellaria. The exact relation of these ducts 
to the duct from the germ gland was not certainly made out, but they 
were so far traced as to show that they unite with that duct near the 
median line on the dorsal side of the germ gland not far from its pos- 
terior border. 
