226 S. J. JOHNSTON. 



sucker 0*203 mm. in diameter, is rather smaller than the 

 ventral (0*239 mm.). The oesophagus is short (0*144 mm.) 

 and the intestinal limbs very narrow. The genital pore 

 lies nearer the anterior end than usual in other species, 

 being nearer the oral than the ventral sucker. The cirrus 

 sac, with the contained vesicula seminalis, lies mainly 

 anterior to the ventral sucker, but with its base projecting 

 backwards for a short distance behind the anterior edge of 

 it. The testes are large and oval with the long axis longi- 

 tudinal, while the oval ovary has its long axis transversely 

 placed. The three gonads are placed close together in a 

 line, one behind the other, without any loops of the uterus 

 separating them. The posterior testis is always slightly 

 smaller than the anterior, the measurements being 0*214 x 

 0*161 mm., and 0*239 x 0*171 mm., respectively. The ovary 

 is considerably smaller, 0*107 x 0*161 mm. The recep- 

 taculum seminis and gland of Mehlis lie just posterior to 

 the ovary. 



The yolk glands, as in L. parvum, are few and large, 

 occupying a short field in the body immediately behind the 

 ovary. They are arranged in an irregular double row and 

 are greatly obscured from view by the uterus filled with 

 eggs. The whole of the posterior part of the body is taken 

 up by the folds of the uterus. 



The eggs are large, the largest measured being 0*041 x 

 0*024 mm., the smallest 0*037 x 0*021 mm., while the 

 average of a large number measured was 0*038 x 0*023 mm. 



Lyperosomum harrisoni, sp. n. 



Diagnosis. — Elongate, cylindrical; suckers large, but 

 not so wide as the body, oral sucker smaller than the 

 ventral. Testes large, oval in shape ; posterior larger than 

 anterior; ovary oval. Long axis of both testes and ovary 

 transversely placed. Genital pore midway between the 



