ART. 6. ANATOMY OF DINOBOTHRIUM LINTON. 6 



Bothria four, in pairs corresponding in position with the flat 

 sides of the strobile, and acting as cupping disks. The mucous mem- 

 brane, upon removal of the worms, was congested, the capillaries 

 showing plainly in four spots where the bothria had been applied. 

 The scoleces changed shape but little when placed in killing fluid. 

 There are small suckers at the anterior ends of the bothria unlike 

 any that I have seen before in selachian cestodes. Strobiles evi- 

 dently all immature, much contracted, with a tendency to twist and 

 crumple, and difficult to straighten. Ten scoleces were found in the 

 spiral valve of this shark. Associated with them were 50 or more 

 cestodes belonging to the genus Phyllohotlirium. 



No measurements of the strobiles are given in my notes. The 

 longest alcoholic specimen measures about 20 mm. in length, 



Scolex. — Details of the structure of the scolex are shown in figure 

 1, the outlines of wliich are from a specimen mounted in balsam. 

 A front view of the scolex is shown, and at the same time a full- 

 face view of the bothria. Specimens in alcohol do not differ ma- 

 terially from the sketch, except in the more or less cup-like char- 

 acter of the bothria. In most cases the bothria flare widely so as to 

 look forward, a line normal to their surface making an angle of 

 from 30 to 45 degrees with the axis of the scolex. In all cases the 

 bothria have thin edges and present a characteristically clean-cut 

 appearance. The bothria are dorso-ventrally placed, that is, corre- 

 sponding with the flat sides of the strobile. The anterior end of the 

 scolex is flat, and, in dorso-ventral view, makes a straight line at 

 right angles with the axis of the scolex. A single bothrium has the 

 following characters : The general shape is like that of a deep scoop , 

 becoming in some cases cup-like. The outer, or lateral, border is 

 convex; the inner, or median, which lies close to the inner border of 

 its mate, is straightish. At the middle of the posterior free border 

 there is a short groove, each of the sides of which rises into a short, 

 almost papillary, projection. The anterior end is thick at the back, 

 where it is continuous from one bothrium to the other of the same 

 pair, and is reflected in a double, shelf-like projection, each portion 

 of which terminates in a pointed tip at the median border. Toward 

 the lateral border the two shelves blend and continue in a curved 

 fold which is bifurcate at the tip. The outer or anterior portion of 

 the projection is thickish and forms a sucker-like depression. The 

 inner portion of the projection is thin edged. The pointed tips 

 appear to be rigid and almost hook-like (fig. 4). Sections of the 

 bothria (fig. 5) show that they are made up, for the most part, of 

 short, thick muscular fibers at right angles to the flat surfaces. 



A striking feature of the bothria of this species is the furrow at 

 the middle of the posterior border. This is not an accidental con- 

 traction character, but is present in each bothrium in each of the 



