STUDIES OX THE ECTOPARASITIC TREMATODES OF JAP AX. 39 



syncytium (PI. XVII, fig. 6). They are distributed, both on the 

 ventral and dorsal sides (PL XVII, fig. 5), into two groups, the 

 right and the left ; and the cells of each group discharge their products 

 into a common large duct'^ provided with a distinct membrane, which 

 opens by a minute aperture on the ventral surface of the lateral portion 

 of the body, at a short distance from the stalk of the sucker (PI. 

 X^II, fig. 12, gl'). The secretion of these granular cells is a very 

 granular fluid, the granules staining very deeply in haematoxylin. 



Tristomum and Epibdella — As has already been observed by 

 Monticelli,^^ there are, in these genera, numerous unicellular glands 

 in the anterior portion of the body ; and in some species of Tristomum 

 (T. sinuatum and T. biparasiticum) there is in addition a series of 

 groups of unicellular glands which open at regular intervals along 

 the lateral borders of the bod}^ 



The cells of the anterior sticky glands are more or less goblet- 

 shaped, with a very thin membrane, a more or less granular cyto- 

 plasm, a nucleus with a single nucleolus, and a long neck. The 

 nucleus sometimes occupies the central position, but is sometimes 

 quite peripheral. The cells are distributed almost uniformly, or in 

 groups separated from one another by dorso-ventral muscular fibres, 

 in the mesenchyma of the suckers and of the anterior, median portion 

 of the body. In some species of Tristomum (as in T. ovale) the necks 

 of the gland-cells open at various points on the venti-al surface of the 

 sucker, at the tops of small, conical papillae (PL XXII, fig. 5), and 

 especially along the inner border of the sucker, where the papillae are, 

 as already mentioned, larger and very numerous (fig. 5). In T. 

 sinuatum the glands open mainl}?^ along the margin of the anterior 



1). Its size, however, probably varies according to the quantity of its content. 



2). MonticeUi— Di alcuni organi di tatto nei Tristomidi : Bollet. della Soc. di Xaturalisti 

 in Napoli, Ser. 1, Anno 5, vol. V., 1891, fas. 2. 



