STUDIES ON THE ECTOPAEASITIC TBEMA.TODES OF JAPAK. 29 



and the circular. The radial fibres must again be divided into two 

 groups. In one they are direct continuations of the longitudinal 

 fibres of the body, and on entering the sucker diverge irregularly more 

 or less in all directions, and are inserted, some to the elevation that 

 forms the wall of the central polygon, others to the periphery of 

 the sucker. The other group of radial fibres includes those fibres 

 which start from the central polygon, and pissing along the radial 

 elevations, are inserted in the periphery of the sucker. The transverse 

 or dorso-ventral fibres merely traverse the thickness of the sucker, and 

 are inserted into the basement membrane. Like the dorso-ventral fibres 

 of the other parts of the body, they ramify into a number of small 

 branches towards their ends. The circular fibres are present only 

 on the dorsal side ; they are arranged in circles concentric with the 

 circumference of the sucker, and are comparatively few. The inter- 

 spaces between the muscular fibres are filled by a connective tissue 

 similar to that of the body (PL XIX, fig. 6). 



. Monocotyle — Morphologically speaking there is no anterior 

 sucker in this genus, but physiologically speaking there is. The 

 dorso-ventral as well as the cu'cular fibres of the body, namely, are 

 strongly developed at the anterior end around the mouth (PI. XVIII, 

 fig. 4), so that the arrangement of muscular fibres is very similar to 

 that which obtains in the anterior suckers of Onchocotyle and of the 

 distomes. There is even a sort of marginal membrane on the ventral 

 lip (PL XVIII, fig. 4, a). That this anterior portion acts as a sucker 

 is beyond doubt ; for I have observed the worm execute an active leech- 

 like locomotion by alternately attaching and detaching the mouth and 

 the posterior sucker. In fact, the structure here described is a prelim- 

 inary step to the formation of such anterior sucker as that of 

 Onchocotyle and the distomes; the only difference being that in the 

 latter, the sucker has been distinctly separated fi*om the surrounding 



