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eans, thus demonstrating a primitive condition. The prolongation of the 
ductus ejaculatorius in Enterogonia to a long sinuous tube, of value 
when the penis is protracted, I regard also as a substitute for the 
missing seminal vesicle. 
The location of the ductus ejaculatorius is never irregular. This 
median duet runs always ven tral to the prostatic vesicle, when 
the vesicle is horizontally or obliquely placed in a forward direction. 
By a vertical position of the prostate, as in Cryptophallus and 
Par asty lochus, the duet is found an te ri or to the vesicle. It is 
evident that this'position is in full correspondence to the former case. 
The joining of the ductus ejaculatorius to the efferent duet of 
the prostatic vesicle takes place consequently on the anterior side 
of the latter. For the common duet, thus resulting, it may be of 
advantage to use a special name, penis canal. The length of 
it varies considerably, the extremes found in Enterogonia and 
Parastylochus. From a phylogenetical point of view, as also with 
regard to the actual condition, it is, of course, wrong to say, as 
some authors do, that the ejaculatory duet receives the duet from 
the prostatic vesicle, when just the opposite is the case. 
A more primitive way of establishing connection with the prostatic 
vesicle is found in Plehniidæ and Polyposthiidæ. Meixneria and 
Idioplana show therein a certain resemblance to them, in full 
accordance with my view that these families are closely allied to 
Stylochidæ. 
Key to the Stylochid genera. 
A key of determination for the Stylochids was given in my 
paper of 1913, when I ranked them as a separate family. In 1920 
Yeri and Kaburaki described a new genus, Neostylochus, and alter¬ 
ed then the second part of the key. In treating a member of this 
genus I had the opportunity to correct some mistakes in that paper 
and consequently revised the key up to date. Although this was 
done so recently, there is, however, no question about the neces- 
sity to present a new key, since the knowledge of the Stylochids 
has been extremely inereased through the studies of Dr. Morten- 
sen’s collections. In the previous year we counted only eight Sty¬ 
lochid genera, now there are not less than fourteen. The new 
members are, as already enumerated: Enterogonia Haswell 1907, 
