MORPHOLOGY OF MELIBE 567 



(2) The Hermaphrodite Duct. 



Mazzarelli (1891 a) found that the hermaphrodite duct which 

 leaves the male-female gland is very minute in diameter at its 

 beginning, but later, after a certain descent, dilates abruptly 

 to a greater lumen. From this point it gradually narrows again 

 only to bifurcate, giving origin to two minute ductuli. From 

 this point one passes straight to the penis (oedagus), in which 

 it constitutes the deferent channel. The other ductule which 

 is the oviduct enlarges rapidly after its origin and here presents 

 a tiny caecum, then the oviduct contracting gradually, only 

 again abruptly to dilate, develops the first ampulla. In 

 M. leonina, however, I find that the hermaphrodite duct 

 has separated into two distinct male-female ducts, i. e. from the 

 time an exit is formed in the acinus it is double. It should be 

 pointed out, however, that the male duct caudad of the ampulla 

 is larger than the corresponding female duct. 



(3) The Oviduct. 



The oviduct, after it leaves the last acinus (PL 37, fig. 81, Od), 

 passes into the prostata (Pr), which, in fact, is a part of the 

 female duct. It stands in relation with the ampulla of the 

 vas deferens by a biluminate duct {Bil.dpr) (PI. 37, figs. 73, 79, 

 Pro) ; the so called prostate gland is a much-coiled portion of 

 the oviduct, consisting of two kinds of coils, a large and a small 

 coil system coiled upon itself. The ampulla-prostate duct shows 

 that the female-duct system formerly was in functional relation 

 with the male-duct system at the ampulla ; the genital-duct 

 system from the ampulla and to the gonads constituted the 

 hermaphrodite duct. At the point of exit from the prostata 

 the oviduct dilates into a much saccular portion (PI. 37, figs. 79, 

 Ut, 80, F, 81, Ut), which after some distance passes into a 

 narrow portion. From the distal part of this (PI. 37, fig. 81, Osp) 

 there is a large sac, the spermatotheca, and from this point 

 to the orifice the duct dilates a little {Va) forming into what 

 I have called the vagina. The most distal portion of the 

 duct lies in communication with the mucous gland {Mgl). 



