DEVELOPMENT OF PARAVORTEX GEMELLIPARA 



467 



masculiiium at the lower end of the seminal vesicle, is directed 

 through the common atrimn toward the genital pore (text fig. 1). 

 In no worm whose testes had become fmictional was the seminal 

 vesicle found empty; usually it is distended with a mass of 

 spermatozoa. All these organs are surrounded by a cellular wall. 



Text fig. 1. Sagittal section of Paravortex gemellipara. X 167. 



Text fig. 2 Optical frontal section from below, ant., antrum; at., atrium; 

 cap.jcapsules; ^.p., genital pore; int., intestine; ??i., mouth; o, ovAvy: ph., pharynx ; 

 S.V., seminal vesicle; gl.sh., shell glands; t, testis; vit., vitellarium. X 167. 



In half-grown worms the male reproductive organs have reached 

 maturity; after this period the testes with their ducts undergo 

 partial degeneration. Patterson states that they are seldom 

 found in large individuals, but I have seen them in every speci- 

 men examined. 



JOURNAL OF MORPHOLOGY, VOL. 27, NO. 2 



