NEW PARASITE FROM THE CRAYFISH. 



6 9 



ventrally, and marking off a lateral area, containing the vitellaria 

 and the intestine, from the'center (see Fig. 5). There are no 

 horizontal parenchyma muscles. Cells of the parenchyma directly 

 underlying the body wall are especially numerous and glandular 

 in appearance, as often in trematodes. 



The oral sucker opens widely downwards and forwards. It is 

 composed of the usual muscular masses, enclosed within a fine 

 structureless membrane marking it off from the parenchyma. 

 The detailed struct me of the papillae is indicated in Fig. 4, which 

 is a camera lucida drawing from a section passing through the 



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FIG. 6. General view of the reproductive organs, seen dorsally. 



oral sucker in the level of the lateral papillae and through their 

 length. Sections through the four anterior papillae show the 

 same things. The wall of the oral sucker, consisting of a layer 

 of parenchymatous tissue and masses of radial fibers, is pushed 

 out at the bases of the papillae, the connective tissue portion be- 

 ing directly continuous and the muscle fibers pushed aside at 

 that point, and passes up to the summit of the papilla, a new set 

 of radial fibers being added in the papilla similar to those of the 

 general wall of the sucker. The papillae are thus not merely 



