g S. GOTO. 



the appendage, which is usually the case in other genera ; and (3) 

 that according to this view the apparently dorsal side on which the 

 suckers are borne, is really the ventral side, a fact in harmony with all 

 the cases hitherto known. 



In Monocotyle (PI. XVII) again, the body is much flattened, 

 and its cross-section presents almost the form of a crescent whose 

 inner side is ventral. In general outline the body is elongated, 

 broad, and a little bordering on the oval. The posterior end is 

 quite sharply pointed. • Anteriorly the body becomes narrower, 

 but again somewhat broadens out in front, where at the end 

 there is a large, shallow notch (PI. XVII, figs. 1 & 2). 

 In Galicotyle (PL XIX), the shape of the body is that of an 

 ovate, heart-shaped leaf, its apex forming the anterior end, 

 and its basal notch bearing the posterior sucker (PI. XIX, figs. 

 1, 2, & 3). 



In Tristomum (Pis. XX — XXV), the body is mostly notched at 

 the posterior end, and its form varies from that of an orbicular to that 

 of an oval or ovate, heart-shaped leaf with apex more or less 

 truncate ; the truncated border being sometimes convex, sometimes 

 concave, and sometimes almost straight. In Epibdella, the body presents 

 the same general outline as in Tristomum, except that the posterior end, 

 instead of being notched, becomes gradually narrower and is directly 

 continued into the sucker. 



2. The Investing Membrane. 



In my paper on Diplozoon^^ 1 called this membrane the epidermis, 

 assuming in so doing that it corresponds to the true epidermis of other 

 animals. I have still no cause for recantation ; but as an antagonistic 



1). This Journal, vol. IV, pt. 1, 1890. 



