STUDIES OX THE ECTOPARASITIC TEEMATODES OF JAPAN. 59 



staining protoplasm. In the species just named, the cells arc cylindri- 

 cal, sometimes attaining the length of ahout .05 mm., and are in some 

 parts closely crowded. But in most of the other species having the 

 intestine of this type, the cells are separated from one another by wide 

 intervals, and the protoplasm is almost entirely obscured by pig- 

 ment granules. In Microcotijle I have not been able to demonstrate 

 the existence of the nucleus, although there was a clear space in the 

 centre of each cell. In Onchocotyle, again, there are, besides the tall, 

 cylindrical cells already mentioned, smaller cells with a well staining, 

 finely granular protoplasm which is either entirely destitute of 

 pigment granules or contains fewer granules of smaller size. Some 

 of these cells are again very small, and have a scanty mass of 

 protoplasm around the nucleus, which latter remains nearly constant 

 in size in all the forms of cells. Intestines of the type above described 

 are found in Microcotijle, Axine, Octocotyle, Diclidophora, Hexacotyle, 

 and Onclwcotijle. 



The second type of intestine is similar to that of the distomes, 

 and is found in Tristomum, Epibdella, Monocotyle, Calicotyle, and the 

 Gyrodactyliilae. In this type, the intestinal cavity is lined by a con- 

 tinuous epithelium consisting of cells which are all similar to one 

 another. The individual cells are either cubical or cylindrical, and 

 have a distinct membrane except on their free bordei's whei'e it seems 

 to be entirely wanting. The nucleus is always situated close to the 

 tunica propria. In Monocotyle Ijimae (PI. XVIII, figs. 2 and 5), the 

 boundaries of the cells are, in cross-section, not to be clearly seen in 

 every- case ; but in a surface view they can be distinctly recognised (PI. 

 XVII, fig. 11). In this species, moreover, the protoplasm of the cells 

 stains deeply, and contains numerous, deeply staining, granules, 

 which are smaller than and also very different in appearance from the 

 pigment granules of the first type. In Tristomum, however, the 



