28 SPECIAL ANATOMY OF THE TERRESTRIAL 



duct is short, gradually increases in breadth, and is spi- 

 rally twisted. From the duct, as previously mentioned, 

 passes a small offset to the vas deferens. The common 

 duct of the bladder and oviduct, or vagina, is cylindri- 

 cal, and, just before terminating, is joined by a short, 

 wide tube, derived from a large, oval sac, which is filled 

 with a dehcate, reticulated substance. This sac is pecu- 

 liar to Vaginulus ; its use is problematical. 



The position of the female orifice of generation has 

 been already stated. 



Helix. The testicle, very unlike that of slugs, is 

 imbedded or commingled with the parenchyma of the 

 posterior or superior lobe of the liver ; and^ instead of 

 having an aciniform appearance, it is composed of fasci- 

 culi of short coeca. It is usually of a lighter color than 

 the liver. The epididymis is long, and generally very 

 much convoluted, and contains a white, silky, tenacious, 

 substance, often distending the tube to a considerable 

 degree, composed of spermatozoa. At its junction with 

 the prostate gland, it always receives the duct of a small 

 accessory gland, composed, in different species of Helix, 

 of from three to nine acini. 



The prostate gland is generally larger than in the 

 Limaces ; in H. exoleta it is unusually large. 



The vas deferens generally corresponds in length with 

 the curve passing from the termination of the prostate 

 gland downwards to the cloaca, and thence to the sum- 

 mit of the penis. In H. exoleta and H. alholahris it is 



