121 



lateral face of the right dorsal sucker ; and (4) fibres from the 

 lateral face of the left ventral sucker run to the median face 

 of the right dorsal sucker. 



(3) A third cross system orthagonal, running dorso ventral and 



latero-lateral, is situated just behind the second diagonal 

 system. Behind this third muscle-cross the great nerve com- 

 missures occupy the central space between the suckers. 



(4) A fourth cross system is found (behind the great nerve com- 



missures) at the base of the suckers ; the fibres of this system 

 insert on the suckers in such a way that : (1) the median faces 

 of the two right suckers, (2) the median faces of the two left 

 suckers, (3) the lateral faces of the two dorsal suckers, and 

 (4) the lateral faces of the two ventral suckers are connected. 



(5) Behind this there appears to be a muscular connection between 



(1) the right sides of the ventral suckers ; (2) the left sides of 

 the ventral suckers ; (3) the right side of the dorsal suckers ; 

 (4) the left sides of the dorsal suckers. I did not notice this 

 system to connect the dorsal and ventral suckers. 



The Suckers. 



The suckers are large and are pointed diagonally outwards and for- 

 wards. A ring formed by a fold of the subcuticula projects beyond the 

 margin of the suckers, giving them greater depth. Externally they are 

 covered with cuticula, similar to that covering the rest of the worm; 

 internally they are separated from the scolex by a very thin membrane. 



The muscle fibres composing the suckers are arranged in the usual 

 manner. The radial fibres are well developed, arranged in small bundles 

 in the middle zone; these bundles spread out slightly both exteriorly and 

 interiorly. The ganglion cells aheady referred to are mostly situated at 

 from the middle to the inner third of the radial fibres. 



A thick layer of muscles is found on the membrane separating the 

 suckers from the scolex. These muscles run parallel to the membrane 

 and are seen lengthwise on transverse sections; the radial fibres pass 

 between these fibres to attach themseh^es to the membrane. Above this 

 layer proceeding away from the delimiting membrane, one finds cross- 

 sections of muscles running also parallel to the membrane, but at right 

 angles to the first layer. These muscles all show a hollow in their middle 

 (or appear annuliform on section). About midway between the two 

 curved surfaces of the siicker (still examining a transverse section) one 

 finds very fine fibrillae, probably muscular, which run from margin to 

 margin of the sucker. They do not keep the exact middle between the 

 cuticula and membrane, but in the centre of the sucker approach the 

 membrane. 



A ring muscle, or sphincter, is seen at the margins of the sucker. On 

 transverse sections one only finds cross sections of its muscle-fibres. This 



