HEEMAPHEODITISM IN MOLLUSCA. 37 



female orifice (Anatinacea), and when the visceral commissure 

 (" connectife cerebro-visceraP') is sufficiently superficial, the 

 female orifice is found lying outside this visceral commissure 

 like the genital orifice — be it male or female — of all 

 the Lamellibranchs (fig. 13). This orifice is accordingly 

 not a new formation. 



But the male orifi.ce is within this commissure (fig. 14), 

 and so presents relations to which no counterpart can be 

 found elsewhere ; it is consequently a new formation, and if 

 it was necessary for a male orifice to be produced as a new 

 formation it is evident that the starting-point of the herma- 

 phrodite condition must have been supplied by the female 

 organism. 



ii. Similarly in hermaphrodite Gastropods the male products 

 are always expelled by a ccenogenetic penial orifice, which 

 is wanting in the archaic dioecious forms (Rhipidoglossa, 

 — as in the Amphineura and Scaphopods), while the female 

 orifice in the same forms lies in the place occupied by the 

 genital orifice (whether male or female) of archaic Gastropods 

 which possess no penis. 



And when an approximation of the two apertures, male and 

 female, takes place — the former approximates to the latter in 

 Arion; vice versa in other cases — the disposition is secon- 

 dary, and is accompanied by an increased complexity of the 

 ducts and their appendages. In the most primitive cases the 

 two orifices are always widely separated (BuUidse among 

 Opisthobranchs; Auriculidse among Pulmonates). 



In the development of the Pulmonata the penis and vas 

 deferens are new formations (48a) which arise secondarily, the 

 vas deferens only communicating at a late stage with the 

 genital duct properly so called (physiologically hermaphrodite), 

 which leads to the female orifice ; that is to say, the genital 

 organs of Pulmonata develop as female organs, which are even- 

 tually modified as as to become hermaphrodite (48b). 



The opinion formulated above (that in Mollusca herma- 

 phroditism is grafted upon the female organism) is confirmed 

 by the following fact. In hermaphrodite molluscs, whenever 



