250 Mr. W. Nicoll on the 



outline, much as Levinsen found it. Such a form is rarely, 

 if ever, met Avith in Sjk excellens or Sp. simile. In con- 

 traction the anterior part of the hodj' becomes broader, 

 almost as broafl as the posterior part, but it is always 

 separated from the latter by a distinct constriction about the 

 level of the intestinal bifurcation. 



In my second series of measurements, specimens were 

 found varying in length from '71 to r39 mm., the average 

 being "91 mm. The maximum breadth of the anterior part 

 of the body is '23-37 mm. ; at the constriction •21--28 mm. ; 

 posteriorly "Sr-'^Q mm. The average of these is '29, "24, 

 •41 mm., being nearly in the proportion 5:4:7, and a large 

 number of examples were found to vary very slightly from 

 these average figures. Both suckers are small and feebly 

 developed : the oral sucker measures "OeS-'OSe mm. in 

 diameter, the ventral sucker •062-"081 mm. ; average 

 •076 mm. and '071 mm. respectively, a ratio of nearly 

 15 : 14. The maximum limit '095 mm. previously quoted 

 for the ventral sucker is apparently abnormal. The ventral 

 sucker is situated at a distance of rather more than ^ of the 

 body-length from the posterior end, and if it be regarded as 

 marking the boundary between the anterior and posterior 

 parts of the body, the ratio between the two is approxi- 

 mately 5 : 3. 



The pharynx measures •037-*062 x •026-^044 mm., and 

 the prepharynx is about | as long. The oesophagus is 

 narrow and may be any length from ^20 mm. to "45 mm. 

 The di\erticula are about | of that length ; they are dilated 

 and extend back as far as the level of the centre of the 

 ventral sucker. In a few cases they stop short of, or exceed, 

 this limit, but the variation in this respect is slight. 



Odhner pointed out a distinction between Spelotrema 

 pygmteinn and Sp. simile, which escaped Jagerskiold^s notice. 

 In the latter species the base of the genital body is much 

 larger proportionately than in the former. In Sp. excellens 

 it is still larger iu comparison with the size of the ventral 

 sucker. It measures -ObO-OQo mm. in diameter, i. e., about 

 ^ the diameter of the sucker. It is situated on the left side 

 of, and close beside, the ventral sucker, which it occasionally 

 overlaps, and it is on a level with the centre of the sucker 

 or, as often as not, a little in front of or behind this. The 

 vesicula seminalis lies in the middle line or a little to the 

 right, immediately in front of the ventral sucker, sometimes 

 slightly overlapping it dorsally. Its outline is elliptical, the 

 long axis being directed obliquely forwards ; size"09-'llx 

 •07-'08 mm. The ductus ejaculatodus^ issuing from its 



