252 Mr. W. NicoU on ihe 



onlv in immature condition in Hamatopns ostralegus awd 

 Variellus vancllus. In every case tlie liabitat is towards the 

 loM'erend of the intestine, the cseea, and the rectum. Occa- 

 sionally a few were found as far forward as the duodenum. 



It is readily distinguished from the other species of the 

 genus by several -well-marked features. The body docs not 

 display the familiar club-like outline, it has more that of a 

 pointed oval, the posterior end being rounded. There is no 

 marked constriction. The examples from Vanellus are 

 bluntly oval, presenting the appearance of a species of the 

 genus Gynmophallus, from which they are certainly hard to 

 distinguish in their immature condition *. 



In point of size it is midway between Sp. simile and 

 Sp. excellens, the observed limits in length being •66--91 mm.; 

 average '77 mm. In a specimen of average length the 

 maximum breadth is "36 mm., and is found at the level of 

 the ventral sucker or a little behind it. The oral sucker is 

 of large size, measuring '09 ram., and is considerably greater 

 than the ventral sucker, which has a diameter of -075 mm. 

 The ratio is 6 : 5. The ventral sucker is almost exactly a third 

 of the body-length from the posterior end. The pharynx 

 has an average length of '065 mm., and the prepharynx is 

 about as long, but it varies with the state of extension. 

 The oesophagus measures "12 mm. in length and the diver- 

 ticula "28 mm. Thus the latter are nearly 2^ times as long 

 as the oesophagus, in marked contrast to the condition in 

 Sp. excellens. Moreover, they extend as far back as the 

 posterior border of the ventral sucker, and they are not 

 dilated. 



The genital body, situated close to the left side of the 

 ventral sucker and rather behind the level of its centre, is 

 comparatively small, measuring only 040 mm. in diameter 

 at the base. The vesicula seminalis is a large ovoid, some- 

 times almost globular body, lying well to the right side of 



* From later observation I am inclined to suspect that more than one 

 species is under consideration here. What must be regarded as the 

 tvpital specimens occur particularly in Pelidna and JEyialitis, and they 

 present some features which are not met with in the other members of 

 the genus. These features I have not touched on above, as I at first 

 considered them ti;) be abnormal ; they are as follows : — The body has a 

 distinct brownish colour, due to the presence of some pigment. The 

 excretory system is mapped out with surprising distinctness in a series of 

 intensely black lines, the configuration of which is much as in Jiiger- 

 skiuld's figure (Centralbl. f. Bakter. xxvii. p. 734, fig. 2), but, in addition, 

 numerous fine anastomosing tubules are also visible. Finally, there is a 

 roundish structure, enclosing apparently two small ovoid bodies, situated 

 between the genital body and the left intestinal diverticulum. Of the 

 function of this structure I have at present no knowledge. 



