MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 173 



the testis. Near the lower edge of this face is a funicular depression leading into thevas deferens 

 (v. d.). The funnel of the testis tits snugly within this opening, so that, as Kerr remarks, 

 "though the cavities of the testis and of the vas deferens open quite independently into the 

 ccelom, they are at least during sexual maturity functionally continuous with one another." 



The vas deferens winds about through the accessory gland, finally passing into a tough- 

 walled sac which occupies most of the anterior end of the gland. The accessory gland "is com- 

 posed of numerous ciecal tubular outgrowths from the duct itself" (Kerr). The proximal end 

 of the vas deferens is exceedingly thin walled and small, being on this account very difficult to 

 trace (v. d 1 .). It is rather less than a millimeter in diameter in this portion, but from the point 

 v. d\ its walls are very thick, the whole tube being about three times its former thickness, while 

 the lumen remains about the same size as before. The thickened portion of the vas deferens opens 

 into the right side of the tough-walled sac (S. V.), 12 millimeters long, occupying the anterior 

 portion of the gland, which we may call the seminal vesicle. The seminal vesicle is easily 

 distinguished without dissection of the gland. 



The opening of the seminal vesicle is just in front of the junction of the mantle with the body 

 wall. The remaining parts of the genital duct can be traced from the mantle cavity. They 

 cause projections of the body wall so that their shape and course can be followed without dissec- 

 tion, but they are easily dissected by removing the integument. 



The seminal vesicle opens by a very small orifice into a thick-walled tube which turns 

 obliquely to the left, toward the center of the body. It quickly enlarges into a good-sized sac, 

 11 millimeters long, the spermatophore sac (Sp. s.). This is incompletely divided into two parts 

 by a longitudinal septum extending into it from the posterior wall, upon the left side of the 

 opening into the sac, nearly to the anterior end (Sep.). Coiled spermatophores are frequently 

 found in the sac, bent around the anterior edge of the septum into a U-shaped mass. The 

 anterior edge of the septum is frequently arcuate, so that the opening from one side to the 

 other of the spermatophore sac is 3 or 4 millimeters in diameter and nearly round. 



From the spermatophore sac a short thick-walled tube leads forward to the penis. 



The penis is a tubular organ -1 to 5 millimeters in diameter, lying in the middle of the ventral 

 surface of the body, its axis corresponding with the longitudinal axis of the body (Fig. 3, P.). 



The walls of the penis are thick and muscular. Its tip usually projects freely from the body 

 wall, and bears a small aperture (P. ap.). This leads into a cavity which divides almost immedi- 

 ately into a right and left portion. The right portion connects with the cavity of the spermato- 

 phore sac (P. r.). The wall of the cavity is thrown into longitudinal folds, which, however, are 

 only found in the contracted condition of the organ. When a spermatophore is in the tube the 

 walls are smooth. 



A flesh}- tube is prolonged posteriorly from the left side of the penis obliquely outward 

 and backward for 8 to 15 millimeters (P. 1.). This ends blindly with a slight enlargement. The 

 left-hand cavity of the penis is continued into this tube. Its walls are folded like those of the 

 right cavity of the penis, but not so strongly. In the enlarged portion the cavity also is larger. 

 Near the end of the tube I have found a very minute, yet distinct opening upon the right side, 

 leading into a short narrow sac parallel to the posterior portion of the larger tube. This sac 

 evidently corresponds to the spermatophore sac of the opposite side. In one of the specimens 

 examined the left portion of the penis was entirely lacking. There seems to be considerable 

 variability in the extent of its development. 



It is in the vas deferens that the spermatophores are formed. Each spermatophore consists 

 of a thick-walled tube of chitin, one millimeter in diameter and five to ten centimeters in length. 

 The lumen of the tube is very small and is tilled with spermatozoa. I have several times found 

 a spermatophore irregularly coiled in the seminal vesicle, or rather one end of it was coiled up 

 here. The other end extended back in the vas deferens as far as the end or a trifle beyond the 

 end of the thick-walled portion. The wall of the spermatophore seemed to be fully formed until 

 near the posterior end. For the last centimeter the wall became gradually thinner and paler, 

 finally disappearing. 



