9(3 , s. GOTO. 



this l;ist piece is imbedded in the wall of the sucker with its lono-er 

 axis coinciding- with tlie minor axis of the sucker. The substance of 

 the wall is boimded, as in other genera, Ijoth towards the meseiichyma 

 and the exterior by a cuticular inembrane, except in the central part 

 whei-e the chitinous piece is imbedded, and where this is in direct 

 contact with the mesenchyma. A strong bundle of muscular fibres, 

 which are direct continuations of the longitudinal fibres of the body, 

 are attached to each of the chitinous pieces of the sucker (1*1, XII, 

 fig. 7). 



Onclwcotylc — The position and structure of the suckers are 

 somewhat peculiar in this genus. 



Anlerior siiclrr — An anterior sucker is distinctly present, although 

 some writers liave dem'ed the fact, and is situated around the mouth- 

 cavity, and presents some resemblances of structure to that of the 

 distomes. In cross-section, it is elliptical in outline, and is seen to 

 occupy nearly the ^nIioIc of this region of the body, merely leaving a 

 small portion of mesenchyma in the lateral parts (PI. XV, fig. 4). 

 The ventral half is iiuich smaller than the dorsal half, just as in the 

 distomes (PI. XV, fig. o). The subst:nice of the sucker consists 

 of connective tissue interspersed with ruiclei, some of which are 

 surroiuided by scanty masses of granuhn- proto])lasm, and of nuiscular 

 filrres, most of which are very fine, and, radially traversing the con- 

 nective tissue, are attached to the basement membrane which separates 

 the substa.nce of the sucker from the investing membrane of the body. 

 Besides these radial fibres, strong muscular fibres which act as 

 s])hincters are present in tlie foremost part of the dorsal half of 

 the sucker (PI. XV, fig. 3, .s;)//.) 



Posterior mclîers — These are eight in number arranged in four 

 pairs, one of which is, liowever, very different both in structure 

 and ])ositi()n from the others. The latter are arranged in a horse- 



