328 PliOCKEDINGS OF THK JI ALACOLOGICAL SOCIETV. 



Duct C, nmninp; from the spermatheca to tlie genital passage in 

 the neighbourhood of the origin of the ])enis, is evidently the 

 customary duct. Duct A, much smaller than the other two, affords 

 an alternative route to the oviduct : it has not, I believe, been 

 previously described and, while it was quite obvious in the three 

 smaller specimens which I examined, it could not be found in the two 

 larger ones which had darts. Possibly therefore it represents some 

 arrangement which is falling into desuetude. Duct B, which for 

 most of its course is the largest of tlie three branches, is the most 

 curious, since it opens below into a thin-walled sac lying round the 

 upper end of the common genital passage and the lower parts of the 

 penis and dart-sac. I could find no opening out of this sac save into 

 duct B ; indeed, I am fairly confident that no other anatomical 

 opening exists. The sac is lined -with simple thin epithelium, as is 

 also duct B in its lower two-thirds, and in none of the specimens did 

 the sac show any visible contents. The appearances do not, therefore, 

 suggest that the sac has any very active secretory function, but 

 rather that it is a reservoir of liquid. In the face of our ignorance 

 of the function of the spermatheca, speculation is hardly proper, but 

 it may perhaps be suggested that when the penis is everted in 

 copulation the sac would probably be compressed and any liquid in it 

 forced along duct B : in this way duct C, and possibly the spermatheca 

 itself, would be washed out into the vagina. Alternatively the sac 

 might act as an aspiratory apparatus on the cessation of copu- 

 lation, though the tenuity of its walls renders this unlikely. The 

 examination of sexually active specimens might throw much light on 

 tlie matter, but these I have not been fortunate enough to meet with. 



The specimen from which the drawings were made had a shell 

 6'4 mm. in diameter : the body was straightened out and probably 

 somewhat stretched before the sections were prepared. 



A, duct A of spermatheca; B, duct B of spermatheca; C, duct C of 

 spermatheca ; a. common genital passage ; S. sac into which duct B opens ; 

 ov. oviduct ; p. penis ; d. dart-sac ; v.d. vas deferens ; d.sj). undivided duct 

 of spermatheca. 



