252 Mr. W. Nicoll on the 



only in immatnre condition in Hienuitoims ostralegus and 

 VaneUus vaneJIus. In every case tlie habitat is towards the 

 lower end of the intestine, the cfeca, 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 does not 

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

 pointed oval, tlie 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 Gynmophallua, from which they arc certainly hard to 

 distinguish in their immature condition ^. 



\n ))()int of size it is midway between Sp. simile and 

 Sp. ecccellens, the observed limits in length being 'GG-^l 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 mm., 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. 

 Las an average length of 'OGS 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 2i 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 regaided as the 

 typical specimens occur particularly in Pelidna and JE(/ialitis, and they 

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

 the fj:enus. These features I have not touched on above, as I at first 

 considered them to 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 distinctne.ss in a series of 

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

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

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

 roundish structure, enclosing apparently two small ovoid bodies, situated 

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

 fuuction of tins structure I have at present no knowledge. 



