280 ON MORE AU I A MIRABILtS^ 



The excretory opening is placed in the middle of the posterior 

 border, while the common genital opening is situated in a de- 

 pression on the middle of the left lateral border. 



The size is moderately large, about 2 mm. long by rather less 

 than 10 mm. broad. The average length of eight specimens 

 measured was 1*94 mm., and the breadth 9*49 mm The largest 

 specimen measured 2*09 mm. long by 10'78mm. broad. The 

 cuticle is thin and smooth, and devoid of spines. 



The suckers are small, shallow, and circular, and are very 

 nearly equal in size, the ventral being slightly smaller than the 

 oral. The average diameter of the oral, measured in eight speci- 

 mens, is 0-213 mm., that of the ventral 0*21 mm. In half the 

 specimens measured, the two suckers are exactly equal in diame- 

 ter, while in the largest specimen the diameter of the oral is 

 0-232 mm., that of the ventral 223 mm. Distance between the 

 suckers 0*475 mm. 



Alimentary Cciria?. — The globular pharynx lies partly dorsal 

 and partly posterior to the oral sucker, and is somewhat smaller 

 in size, its diameter being 0*141 mm. There is no prepharynx, 

 the pharynx being very closely applied to the oral sucker, and in 

 part fused with it. The oesophagus is short (0*174 mm.) but 

 distinct. Diverging from the posterior end of the oesophagus, 

 the two intestinal limbs run out to the lateral aspects of the 

 body, following the contour of the anterior, lateral, and posterior 

 borders, to end near one another, one on either side of the 

 excretory vesicle. Each limb, therefore, is U-shaped (Fig.l). 

 The left loop of the intestine passes the common genital chamber 

 on its dorsal aspect. 



Excretory System. — The excretory pore opens on the middle of 

 the posterior border, and leads into a short, rather narrow pas- 

 sage which opens anteriorly into two more spacious chambers. 

 The latter, which are somewhat pear-shaped but flattened on 

 their median sides, run forwards, to end in the region just 

 behind the ventral sucker. The three chambers together con 

 stitute an essentially Y-shaped excretory vesicle, in which the 

 main stem, however, is short. Each of the upper arms of the Y 

 gives off three main branches on its outer side. The hindmost 



