BY S. J. JOHNSTON. 299 



The mouth-opening is terminal and anterior, and leads into a 

 fairly spacious buccal cavity, which is really an incipient oral 

 suckei", being surrounded by distinct layers of longitudinal, 

 circular, and radial muscle-fibres, so that in sections it presents 

 exactly the appearance of a weakly-developed sucker(Fig.l9). 

 The pharynx, in the form of a muscular, oval bulb, opens directly 

 into this oral sucker, but a diverticulum from the buccal cavity 

 runs backwards, ventral to the pharynx, and for a distance equal 

 to its length, forming a median, unpaired buccal pocket(Fig.20). 

 A median and two lateral groups of large gland-cells are situated 

 behind and to the sides of the pharynx. The ducts of these 

 so-called " salivar}^ glands " are closely applied to the inner sur- 

 faces of the wall of the pharynx for a very short distance, when 

 the}' open into its cavity. There is practically no oesophagus, the 

 pharynx opening directly into the bifurcated intestine. The 

 intestinal limbs are pretty straight when empty; but mostly they 

 are full of dark brown or black granules. When this is the 

 case, the walls are thinner, and their surface somewhat sacculated. 

 They run backwards pretty near the lateral edges of the body, 

 and end in a position dorsal to the cotylophore, and just in front 

 of the posterior pair of suckers(Fig.26). When the uterus is 

 distended, they diverge at the posterior extremities. The trans- 

 verse anastomosing branches characteristic of P. integerrunuyn 

 are quite absent. 



The excretory vesicles(Fig.2l) lie near the vaginal papillae close 

 to the dorsal surface, on which each opens by a minute pore. 

 The main vessels proceed backwards to a position in the posterior 

 end of the body behind the intestinal limbs and uterus, where 

 they join one another. In this region, a pair of branches is given 

 off, which run forwards to near the anterior end, giving off a few 

 smaller branches and capillaries that end in flame-cells. 



The most conspicuous part of the genital system is the ovary, a 

 large oval body lying somewhat obliquely placed on the right 

 side, just behind the vaginal papillae. The testes are in the form 

 of a large number of oval or rounded follicles which, lying closely 

 packed together, begin just behind the ovary, and extend in a 

 single layer on the ventral surface back to a position halfway 



