208 S. J. JOHNSTON. 



twenty-seven spines altogether, an uninterrupted row of 

 flat rod-like spines nineteen in number, with a group of four 

 arranged in two pairs on each of the ventral angles (text 

 fig. 10). They vary little in size (the smaller ones in the 

 text figure are drawn fore-shortened) and measure 0*069 

 X 0'013 mm. The oral sucker is bowl-shaped, rather 

 broader than long (0'085 X 0*107 mm.) while the ventral 

 sucker is very much larger 0*501 x 0*407 mm., so that the 

 ratio of the diameter of the oral to the ventral sucker is 

 practically 1 : 5. 



The distance between the suckers in specimens fixed in 

 sublimate acetic is 0*543, little more than the length of the 

 ventral sucker. In living specimens and in several pre- 

 served ones where the contraction, for some reason, was 

 less marked, this space is much longer. There is a short 

 prepharynx (0*08 mm.) and an oval muscular pharynx 0*107 

 X 0*28 mm. The oesophagus, 0*277 is comparatively long. 

 The bifurcation of the intestine lies anterior to the ventral 

 sucker. The intestinal limbs quickly make their way to 

 the sides of the body and terminate a little in front of the 

 posterior end. The excretory vesicle is very voluminous 

 and divides into two large collecting tubes at the posterior 

 border of the testis, which are continued forwards right 

 into the head collar. These vessels and their branches form 

 a conspicuous feature in transverse sections. 



The genital pore lies immediately in front of the anterior 

 edge of the ventral sucker, to the centre of which the 

 cirrus sac reaches back. The testes are triangular or three 

 lobed, with the base of the triangle anterior and the apex 

 pointing backwards. 



They lie in the middle line and in the middle of the space 

 between the ventral sucker and posterior end : but the 

 exact position is variable a little, e.g., in the specimen from 

 wjiich figure 5 was drawn they are a little nearer the 



