250 Mr. W. Nicoll on the 



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

 if ever, met with in Sj). exceUens or Sp. simile. In con- 

 traction the anterior part of the body becomes broader, 

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

 separated from the latter by a distinct coustrictiou about the 

 level of the intestinal bifurcation. 



Ill my second series of measurements, specimens were 

 found varying in length from '7\ to 1*39 mm., ihe 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 •37-*49 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 veiy slightly from 

 these average figures. Both suckers are small and feebly 

 developed : the oral sucker measures 'OGS-'OSG 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 appcirently 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 tlie 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 q of that length ; they are dilated 

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

 ventral sucker. In a {ev^^ cases they stop short of, or exceed, 

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



Odhner pointed out a distinction between Spelotrema 

 pyymamm and Sji. simile, which escaped JagerskiokPs notice. 

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

 larger ])roportionately than in the former. In Sp. exceUens 

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

 sucker. It measures 'OSO-^OGS mm. in diameter, i. e., about 

 4 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 tliis. 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 outluie is elliptical, the 

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

 "07-'08 mm. T'he ductus ejaculatorius, issuing from its 



