152 
other sides (Plate IV, Fig. 32). Beadlike and stout, the intestinal 
coeca only branch and have no ventral pouches as in Cryptophallus^ 
The testes and ovaries have the usual position. 
It might further be mentioned that the female opening lies at 
the beginning of the sixth part of the body, or 5 V 2 mm. from the 
posterior margin at a body-length af 34 mm. The interspace between 
the sexual pores is IV 2 mm., and the distance between the male 
aperture and the pharyngeal pocket is only a little more than the 
distance from the former to the female pore (text-fig. 30). 
It remains to consider the systematic position of the genus 
Enterogonia. As already mentioned, its ranking in the Stylochidae 
caniiot be doubted. The distribution of eyes, the presence of tentacles 
— even if only of a rudimentary nature —, the rich folding of 
the pharynx, the deep pharyngeal side-pockets, the intestinal system, 
the structure of the body-wall, the location of the pigmentation, 
the consistency of the animal, etc. — all harmonize in a decided 
way with conditions already found characteristic of the Stylochids; 
nor do the features of the genital organs forbid the transferring of 
the genus into this family. The confirmation of its relationship to 
the Stylochids has just been shown and firmly established through 
the study of the male apparatus. It is certainly true that most 
Stylochids have a large, highly developed, and in a pronounced 
way specialized vesicula granulorum, provided as it often is with 
radial chambers in its interior. But representatives of this family 
are also known that have such a prostatic vesicle of a simple 
structure and of a pronounced small size. These genera, Crypto- 
phallus and Parastylochus, show at the same time a dislocation of 
the vesicle into a vertical position just above or in the penis. 
Otherwise the vesicula granulorum lies horizontally, always above 
the seminal vesicle. This characteristic dorsal location of the 
prostate is retained in Enterogonia. Nor does the rudimentary nature 
of this organ conceal that it doubtlessly belongs to the Stylochid- 
type, as its proximal part is free. That the prostatic vesicle must 
be separate is a „conditio sine qua non“ for a Stylochid. Unpar- 
alleled in the family is, on the other hånd, the faet that there 
are no seminal vesicles. This condition must originally have been 
primitive in the Polyclads. In Ilyplana, described above, we meet 
