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vagina (text-fig. 9). The cells seem to represent young epithelial 
cells, but they are of a rather embryonic appearance, and no lumen 
is visible between the iwo rows. It is not improbable that this 
string represents a suppressed rudiment of a ductus vaginalis. A safe 
conclusion is, however, not possible from the conditions in the 
single specimen, as the appearance is a little too vague and there 
is no visible change in the wall of the vagina, where the string 
comes into contact with its ventral limb. It would be interesting 
to obtain more specimens of Ilyplana for a study of this mere 
rudiment of a ductus vaginalis. In spite of the very feeble develop- 
ment of this formation, I think that I am right in making the 
interpretation, but for full proof more specimens are desirable. 
A discussion of the systematic position of the new genus 
cannot be omitted. It is at first obvious that the organization- 
features give relatively few holds for a settlement of its relation- 
ships. The shape of the body and the outer appearance of the 
animal present no striking features and do not allow a guess as 
regards the family to which the animal belongs, but only suggest 
that it is an Acotylean of rather indistinct type. According to my 
experience, such conditions are only met with in the Polyclads 
living in mud. When examining the specimen in alcohol, I could 
not, as the eyes were hidden, distinguish it with any certainty 
from the Leptoplanideans. The distance between the tentacular 
rudiments was, however, suspicious, as well as the location of the 
genital pores near the posterior end of the body. As a rule a 
Leptoplanidean has a narrow, prolonged tail-end and the genital 
apparata located more anteriorwards. But Stylochoplana pusilla 
Bock 1924 proves that the rule is not without exception. The 
arrangement of eyes conforms to the Stylochid-type and the location 
of the genital pores agrees perfectly with that of Stylochus. Seeing 
the specimen mounted in oil, I was able to detect the marginal 
eyes and accordingly at once suspected its being a member of 
Stylochidae. There are several Stylochids deviating from the charac- 
teristic Stylochid-appearance as it occurs in Stylochus, Idioplanoides, 
Par asty lochus, Kaburakia, and Cryptophallus. Indifference in outer 
appearance show, for instance, Neostylochus and Leptostylochus. The 
arrangement of eyes conforms to the Stylochidean type, but simi- 
