732 ON SOME TREMATODE PARASITES, 



These two species are obviously very closely related to H. opis- 

 thotrias, Lutz, parasitic in a South American marsupial, appar- 

 ently more closely related to it than to any other species of Ilar- 

 mostomum. They differ from it chiefly, as far as one can judge 

 from the descriptions given by Lutz(13), and later by Braun(2) 

 (though Braun probably had to do with another species), in the 

 very different relations in size of the suckers, in the different rela- 

 tive sizes of the testes, in the size of the eggs, and several other 

 very minor points. But these three (or four) species from mar- 

 supials agree so closely in so many characteristic features, such as 

 the whole structure of the alimentary tract, and the whole con- 

 figuration of the genital system, that they should be looked upon 

 as having been derived from common ancestors. These species 

 from marsupials agree together, and differ from the other known 

 species of Harmostomum, as H. leptostomum Olss., H. (vqrians 

 Lss., parasitic in mammals; and H. fuscatum R., H. marsupium 

 Brn., H. centrodes Brn., H. mordens Brn., H. caudale R., parasitic 

 in birds, in the fact that neither the coils of the uterus, nor the 

 yolk-glands extend anteriorly beyond the ventral sucker. 



A second species of worm from Dasyuriis viverrinus, and that 

 parasitic in the dudodenum of the platypus, I have found it neces- 

 sary to refer to a new genus. 



M E H L I s I A,* gen. nov. 

 Fasciolid trematodes of moderate size, elongated and narrow, 

 leaf-like, thick; widest just behind the ventral sucker, with a con- 

 striction in front of this (Fig. 3). Integument spiny, cuticle thick. 

 Suckers large, near together. Praepharynx, pharynx, no oesopha- 

 gus, intestinal limbs extending to near posterior end. Excretory 

 vesicle with main stem reaching testis, and dividing into four 

 longitudinal branches that form an anastomosing network in an- 

 terior end of body, opening into a sinus surrounding oral sucker; 

 a similar sinus round ventral sucker; ciliated vessels and supple- 

 mentary vessels present. Genital pore near midline, in front of 

 ventral sucker. Copulatory organs present. Testes large and 



Named from the gland of Mehlis, which is of very large size. 



