62 CONTRIBUTIONS TO AMERICAN HELMINTHOLOGY. 



"witliout distortiiig some part of it. The only way to obtain a correct 

 view of the structure of the suckers, is to examine them in the first 

 place with incident light before they have been subjected to pressure. 

 I believe that Fig. 8 conveys a correct interpretation of the disposition 

 of the parts of the framework. 



The suckers have short muscular pedicels and an oval aperture, 

 the long axis of which is directed transversely to the caudal disc, and 

 which has a nearly continuous chitinous ring. This ring is interrupted 

 by hinges at four points in its course, viz., the middle points of the 

 outer and inner bordere, from each of which a hook arches over the 

 aperture of the sucker, and the middle points of the anterior and 

 posterior borders, where it meets with a mesial piece which traverses 

 the concave floor of the sucker. I have never been able to establish 

 the continuity of this with the anterior border of the ring, and am 

 inclined to believe that they do not meet. 



The aperture of the sucker may be narrowed so as orjy to leave a 

 chink between its approximated anterior and posterior borders. This 

 is effected by the outer and inner hinges, and the appearance of the 

 framework is changed by the gi-eater curvature thus given to the 

 mesial piece, and by the free hooks being pressed backwards toward; 

 the posterior border. I believe that Leuckart's figure is drawBi 

 from the framework in this position ; in which case.it is possible to 

 identify the pieces shown in both figures. 



The aperture of the sucker may also be narrowed in a direction at 

 right angles to the above, in which case the hinges from which the 

 free hooks pi-qject become more apparent. This seems to agree better 

 with Olsson's figures (loc. cit.) of the suckers in various species of 

 Octobothrium. 



The mouth-suckers are somewhat peculiarly formed, the muscular 

 tissue being interrupted at the inner margin of each (Fig. 20, PL II.). 



The intestinal coeca are invested throughout by a thick layer of 

 vitelligenous glands, forming two dark-coloui*ed stripes in the body, 

 on each side of and between whioh a somewhat more translucent area 

 is to be seen. 



The abundance and opacity of these glands render the eajamination 

 of the genital organs difficult ; the foMjowing poiate were, howevesj, 

 made out. 



The only genital orifice detected is situated 0.78 mm. from the 

 anterior end. It is a (arculajF sucker of 0^135 mm. diameter^ which^ 



