STUDIES ON THE ECTOPAtHSlTlC TßEMATODES OF JAP AX. 21 



bottom of the suckers. The meduiii piece (c) is also iaibadded in the 

 substance of the wall, and has the form of a regular V, one arm of 

 which lies in the anterior and the other in the posterior wall. The 

 two ends are however somewhat different in form (PI. Ill, ûis. 1). 

 In the anterior wall the median piece ends with two spine-like processes 

 diverging from each other and almost meeting the ends of the lateral 

 pieces. In the posterior wall, on the contrary, these processes are 

 very much shorter and blunter, jind the piece bears between them a 

 dngger-shaped, hollow, terminal piece (PI. Ill, fig. 1). In cross- 

 section, the median ])iece presents for the greater part of its whole 

 length, a rectangular outline, and is seen to be hollow. A little above 

 the bottom of the sucker its cross-section presents the appearance 

 drawn in fig. 7 (c on the upper side), PI. II. 



In Axinc the number and relative position of the cliitinous pieces 

 are just the same as in Microcotijle (PI. A'll, fig. i2). The internal 

 hollow of the median piece is, however, divided in A. licteroccrca into 

 numerous compartments by thin septa. This piece presents also a 

 termination in the posterior wall which is somewhat different from 

 that in Microotijle and is figured in fig. 2 ir, PL VII. 



The anterior and posterior walls of the posterior sucker are very 

 thick and are directly continuous with each other at the bottom of the 

 sucker. Their substance consists of numerous prismatic, very refract- 

 ive fibres closely appressed to one another and leaving a very thin, 

 deeply stained layer of connective tissue batween. These fibres are to 

 all intents and purposes exactl}" similar to those of the anterior suckers 

 (PI. Ill, fig. 7 & PI. A'll, fig. 4). The wall is entirely surrounded 

 on all sides b}' a thin cuticular membrane. In Axine, however, the 

 cuticle of the internal surface is chitinized in parallel zones running 

 parallel to the slit-like mouth of the sucker (PI. VII, fig. 4). The 

 lateral walls of the posterior suckers are very thin and membranous. 



