1910.] 



ENTOZOA OF THE HIPPOPOTAMUS. 



249 



The pars prostatica is pyriform, but, for the size of the animal, 

 is relatively small. 



The ejaculatory duct is only 0*01 mm. long. 



The ductus hermaphroditicus is about the same length and 

 opens upon a stunted crateriform thickening of the atrial wall. 



The yolk-glands extend from the level of the base of the oral 

 opening to that of the dome of the ventral sucker. They also 

 stretch inwards dorsally over the gut towards the middle line. 

 The follicles are large, irregularly arranged masses, 0*5 x 0*3 mm. 



The ovary is an oval body 0*8 mm. in dorso-ventral and 

 045 mm. in antero-posterior diameter, lying almost in contact 

 with the dome of the ventral sucker. 



Text-fig. 34. 



Paramplristomum jpisum. Median longitudinal section. 



The shell-gland mass is situated lateral to, and a little behind, 

 the ovary. It lies in contact with the dome of the ventral sucker 

 and the under surface of the posterior half of the excretory 

 vesicle. 



The uterus is a widely dilated tube almost 1 mm. in diameter, 

 filled with eggs measuring O15x0 - 07 mm. 



Laurer's canal follows an almost straight course from the 

 shell-glands to the dorsal surface, crossing the excretory vesicle at 

 about its middle and opening about 1*4 mm. behind the excretory 

 pore. 



The excretory vesicle discharges by an excretory pore situated 

 about 1*4 mm. in front of Laurer's canal, and from this opening 

 its fissure-like cavity (0*15 mm. wide) stretches backwards towards 

 the dome of the ventral sucker for a distance of 1'5 mm. 



