Four species of Microcotyle. 239 



the connections of the vagina, or to recognise definitely aiiy recepta- 

 ■ciilum seminis or a canalis genitointestinalis. Possibly when rnore 

 xnaterial is secured this may be remedied. 



The acconipanyiiig Sketches will give a better idea of the cha- 

 racter of the suckers than any description, for they are of com- 

 plicated structure (Fig. E). They vary in size, growing larger 

 toward the middle of each lateral row and smaller at the root of 

 the foot and at its tip. Somewhat elevated upon pedicels, their 

 aperture is transversely flattened so that there is an anterior and 

 a posterior half which close together like the jaws of a trap or the 

 metal rims of a purse. 



The suckers are composed of thick muscular walls in which 

 the fibres are arranged radially to the lumen as in other suckers, 

 but they differ from others in the possession of a chitinous skeleton. 



The suckers are composed of thick muscular walls in which 

 the fibres are arranged radially to the lumen as in other suckers 

 T3Ut they differ from others in the possession of a chitinous skeleton 

 ■embedded completely in the muscle so as not to project freely any- 

 where. One might at flrst sight receive the Impression that this 

 ■chitinous framework acted like so many double hooks to anchor 

 the worm in the tissue of the host, but more careful study shows 

 that it serves only as a skeleton to give strength to the action 

 ■of the sucker, 



The anterior wall of each sucker has an arrangement of chiti- 

 nous spicules ditferent from that of the posterior wall. There is a 

 median curved sternum like structure which both at the fundus and 

 toward the edge of the anterior lip spreads out into a "Y" shaped 

 ■end. At the fundus there is jointed to it a short piece which ex- 

 tends back into the posterior hemisphere and is prolonged by two 

 narrower pieces. From each of these there runs a rib like frame 

 arching through the muscle of the posterior half of the sucker to 

 the lateral angle where it meets similar ribs running from each 

 end of the median plate in the anterior wall. Thus from the lower 

 end there courses a thick bar in the middle of the muscle of the 

 anterior lip to the lateral angle and from the upper end a similar 

 though narrower bar over the fundus of the sucker to the same 

 point. In some cases these two bars are not jointed at the lateral 

 ^ngle but form one piece. The median plate lies near the inner 

 surface. of the sucker and indeed may project into its lumen. Sec- 



Zool. Jahrb. XXXIV. Abt. f. Syst. H 



