528 JOSEPH STAFFORD, 



On the opposite side they run forwards and combine with the same 

 coating of the penis-sack to form a mantle for the sinus genitalis, 

 beyond which they pass into the subcuticular cells of the periphery of 

 the body. That these cells remain less differentiated than those of the 

 penis-sack is in harmony with the simpler end organs of the female system. 



The sinus genitalis (sexual cloaca) receives the anterior 

 openings of both penis and vagina, and its walls are, in fact, made 

 up of the continuation of their musculature. It is short and narrows 

 rapidly to its opening — the porus genitalis — in the middle 

 line between foot and neck. Strong longitudinal muscles, but much 

 weaker than in penis-sack and vagina, hold the heavy terminal sexual 

 organs firmly attached to the outer integumentary system and numerous 

 circular fibres form a closing apparatus between the genital sinus and 

 the cervico-pedal pit. Both muscle layers interknit with the 

 subcuticular muscles and the cuticula is continued into the genital 

 pore. Generally, in my sections, the arrangement would seem to in- 

 dicate that the genital sinus is the direct continuation of the vagina, 

 and that the end of the penis-sack is directed into the vagina or, at 

 least, the two are so curved towards one another as to permit easy 

 entrance of the penis into the vagina, which I have observed take 

 place in living worms. 



We have yet two organs of the sexual system to describe, 

 which were left over because they are more to be considered as 

 supplementary organs, lying away from the main course of the con- 

 ducting appartus. These are the Laurer's canal and the vitel- 

 larium. I shall deal first with the more conspicuous vitellarium, 

 which is a double organ, its two halves symmetrically disposed , but 

 its ducts uniting to a single tube, the unpaired vitelline duct. 

 This enters the oviduct about midway between the Lauuer's canal 

 and the ootype. It is a short canal running backwards in the middle 

 line to a three-cornered enlargement, the vitelline reservoir 

 (Fig. 16 ÄR). The latter is simply the meeting place of the two 

 transverse canals with unpaired vitelline duct similar to the expansion 

 where Lauuer's canal, tuba and oviduct meet. When it is filled with 

 yolk-cells, however, it may assume the appearance of a definite organ 

 of not always the same size or shape. From it project sideways the 

 paired transverse vitelline ducts which, intercepting between 

 them uterus, vas deferens and Laurer's canal, bend upwards through 

 the septum , at each side , and join the lateral longitudinal 

 vitelline canals, along the sides of which are attached the fol- 

 licles of the vitellaria. In my semi-diagrammatic figure I have 



