Some Points on the General Anatomy of Gyrocotyle. 723 



animal, even tho this surface is more strongly convex in the thicker 

 central part of the body. In preserved specimens the ruffled edges 

 of the body are bent over the plane surface and cover nearly or 

 fully the fourth of its area next to each margin. The convex 

 surface is relatively uncovered, except on its lateral slope when the 

 ruffles appear in profile as is apparent from a glance at the corre- 

 sponding surfaces of the worms figured in the plate. The develop- 

 ment of the musculature is associated distinctly with this difference 

 in form. One notes a heavy layer of transverse muscles parallel to 

 the plane surface whereas the corresponding layer is not nearly as 

 well developed on the other side of the body. 



Wagenee designated the surface which carries the canal pore 

 as dorsal and noted the fact that the arched dorsum shows little of 

 the lateral folds while the flat ventral surface, the side with the 

 female pore. is considerably covered by these ruffles in all preserved 

 and somewhat contracted specimens. Lönnberg says also that the 

 ventral surface in much contracted specimens is very flat and even, 

 whereas the dorsal surface is strongly convex. He notes also that 

 the lateral folds turn under and cover in large part the ventral 

 surface, leaving the dorsum bare. Both authors made observations 

 in the living worin and neither intimates any departure from the 

 normal in the orientation of the worm as regards the substratum. 

 lt is accordingly a matter of surprise to read in Kofoid & Wats<>x 

 (1910, p. 1): "Its orientation in attachment thus corresponds to that of 

 the heterocotylean trematode. The face here defined as ventral is 

 the one which the animal always turns to the substratum when it 

 is normally active. It possesses the heavier musculature, and more 

 abundant nerve supply, and does not bear the uterine pore, which 

 is dorsal, but does bear the vaginal pore. The ventral surface as 

 here defined has hitherto been regarded as dorsal." 



Watson (1911) is more difficult to interpret as she writes 

 (p. 366) "in the median dorsal line lies the opening of the Uterus 

 . . . The vaginal opening [is] on the ventral surface and the penis 

 opening on the dorsal surface." This agrees precisely with the 

 previous paper in reversing the ordinary terminology. But later on 

 she writes (p. 367) : "In contracted specimens the folds of the two 

 sides are invariably drawn toward each other on the ventral (canal 

 opening) surface." Now the canal pore does lie on the surface she 

 previously called ventral but never so far as my experience goes 

 on the surface partly covered by the folds. My observations are 



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