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seminal vesicle, and the prostate vesicle is unchambered; i. e. the 
lumen is undivided. Besides, Neostylochus has eyes scattered over 
the entire anterior end of the body, distinet tentacle rudiments, 
and testes and ovaries ventrally and dorsally respectively. 
In addition to a dissimilar shape of the body and arrangement 
of eyes, Idioplana and Idioplanoides have well-developed long ten- 
tacles and a vagina that extends over and far anterior to the male 
apparatus. In both cases the prostate vesicle has a simple organi- 
zation, with radiating tubes lacking, a true seminal vesicle is present, 
and the testes have a ventral location. Idioplana has a minimal 
Lang’s glandular vesicle with a long duet, while Idioplanoides has 
a paired Lang’s vesicle with likewise a long duet. Leptostylochus 
is probably most closely related to these two genera. Limnostylo- 
chus, with one fresh water species and two in brackish water in 
south-eastern Asia, seems to me to be more dissimilar, so that I 
shall simply refer the reader to Stummer-Traunfels’ and Kaburaki’s 
descriptions. 
The new genus receives the following diagnosis: Stylochids with 
thin and delicate body. Marginal eyes only in anterior half of body.. 
Separated cerebral eye-clusters and few tentacular eyes. Frontal 
eyes absent. Tentacles rudimentary. Pharyngeal apparatus exceed- 
ingly elongated and narrow, with small side-pockets. Intestinal 
coeca with ventral projections. Gonads intermixed dorsally. Genital 
pores close to each other. Penis small, unarmed, and without 
penis-sheath. Chambered prostatic vesicle and two false seminal 
vesicles. Vagina moderately long, with muscle sphineter and expanded 
Shell giand duet. Lang’s glandular vesicle unpaired and large. One 
species from New Zealand. Another species has been collected by 
myself at Sydney. 
Cryptophallus sondaicus nov. spec. 
(Plate III, Figs. 18-21; Plate IV, Figs. 25-28.) 
Locality: Amboina. On stony beach. 
Mate rial: The only specimen at hånd was collected together with 
Discoplana siibviridis (Plehn) Bock and Stydochus mar- 
moreus n. sp. February 10, 1922, and preserved in 
formalin. 
Habitus: The animal differs from Siylochus in its more elong- 
