64 



Eledone, and communicates with the exterior directly by 

 means of the genital ducts and indirectly by means of the 

 so-called " Water Vascular Canals." These are two long 

 slender duets leading from the genital gland into the 

 pericardium. The right duet is partly shown (fig. 40. 

 W . V. C) where the canal runs dorsal to the right kidney 

 and pericardium, and opens into the latter dorsally, just 

 behind the reno-pericardial opening. In the female there 

 nre two symmetrical canals which are long, slender and 

 thick-walled, and open posteriorly into the genital capsule 

 (PI. V, fig. 39, W.V.C. and a<p. int.) These internal 

 apertures are just exterior to the internal apertures of the 

 oviduct (fig. -'59, /. od. <//>. inf.). [n the male, however, 

 the right canal alone resembles that of the female in width 

 and position, while the left is much wider- particularly 

 in the region near the genital gland — and opens into the 

 genital capsule quite anteriorly (Text fig. VII, A. p. 90). 

 [n both sexes the pericardial pouches and the water canals 

 are lined by ciliated epithelium, and as shown (PI. YI, 

 fig. 51), the water canal follows the course of the sexual 

 duct for the greater part of its length. 



EXCRETORY SYSTEM. 



The Kidneys— a single pair of large transparent sacs 

 are exposed by stripping off the epithelium which covers 

 the visceral mass. They lie on the postero-ventral surface 

 of the visceral mass, ventral to the heart and posterior 

 to the greater part of the alimentary canal (PI. Y, fig. 37, 

 R.K.). The left kidney stretches a little further forward 

 than the right. In young females these sacs may cover 

 the whole postero-ventral surface of the body, but in older 

 females and all males the genital gland pushes them 

 anteriorly and laterally, by its ventral protrusion (fig. 37, 



