171 
Key of determination. 
I. Female apparatus consists only of an S-formed vagina which consequently 
does not emit a duet after receiving the uteri. 
A. Genital pores widely separated. Vagina very long. Prostatic vesicle 
large, horizontal, unchambered; false seminal vesicles; penis-sheath; 
tentacles half-globular; pharynx skort. 
Meixneria Bock 1913. 
B. Both genital pores near posterior margin of body. Vagina short. 
a. Prostatic vesicle small, vertical, unchambered. Tentacles rudiment- 
ary. False seminal vesicles; genital pores not very close to each 
other; pharynx very large. 
Parastylochus Bock 1913. 
b. Prostatic vesicle very large, horizontal, chambered. Tentacles long. 
True or trilobed vesicula serninalis; genital pores close to each 
other; pharynx very large. 
Stylochus Ehrbg. 1831. 
c. Prostatic vesicle large, horizontal, unchambered. Tentacles rudiment- 
ary. Cyanophile antral giands. No discrete seminal vesicles ; genital 
pores close to each other: pharynx primitive. 
Ilyplana n. g. 
II Vagina emits at its inner end a duet running in a caudal direction. Thus 
there is formed a median uterine canal. 
A. The caudal duet opens into a Lang’s glandular vesicle. 
a. Lang’s vesicle unpaired. 
1. Penis unarmed. 
cc. Vagina of extreme length, stretching itself over and in front 
of the male apparatus. Tentacles long. Prostatic vesicle mode¬ 
rately sized, horizontal, unchambered; trilobed vesicula 
seminalis; Lang’s vesicle .small; deep pharyngeal side- 
pockets. 
Idioplana Woodworth 1898. 
/?. Vagina short. Tentacles rudimentary. Prostatic vesicle hori¬ 
zontal, unchambered; false seminal vesicles; Lang’s vesicle 
large; insignificant pharyngeal sidepockets. 
Leptostylochus n. g. 
2. Penis armed with a stylet. Tentacles rudimentary. Prostatic 
vesicle horizontal, unchambered; vesicula seminalis. 
Neostylochus Yeri & Kaburaki 1920. 
