788 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [70] 



diameter of face of botliriuiri, about 1.2 mm ; diameter of neck, lateral, 

 immediately behind head, l mm , a little farther back, .4 mm : distance to 

 first distinct segment, about 23 mm ; length of last segment, 1.5 mm , 

 breadth, l.l mm . The longest specimens in this lot measured, while liv- 

 ing, from 165 to 185 mm . 



The head of the living worm in lateral view appears to be distinctly 

 bi-lobed, and very broad. In marginal view it is quite narrow and ob- 

 long. Upon a closer examination it will be seen that what appears to 

 be one of two marginal lobes is really a marginal pair of bothria. The 

 latter in the living worm are capable of considerable change of form. 

 The edges are constantly changing their outline, but are usually more 

 or less crinkled or raffled. This sometimes assumes an apparently 

 ragged appearance, but in no case, so far as I have observed, are the 

 edges of the bothria tattered. 



The specimen obtained August 8, 1887, was studied while living rather 

 more carefully than any of the others, and some features noted that were 

 not observed in other cases. I append the following data from notes 

 made while observing the living specimen. 



The length of the specimen was 50 ,nm ; length of pedicels about .4 mm ,• 

 diameter of pedicel, lateral view, .28 mm ; breadth of head at bases of 

 pedicels, lateral view, .72 mm . Bothria thin, leaf-like sessile on the pedi- 

 cel which bears each marginal pair. From the manner of their attach- 

 ment it is difficult to make out their shape. At rest the pedicels point 

 forward with p,n interval between equal to a little less than the diameter 

 of a single pedicel. The bothria appeared as if bent around the end of 

 the pedicel so that one edge curved into the space between the pedicels, 

 while the opposite edge bent around until it touched the margin of the 

 neck. Each bothrium bears an auxiliary acetabulum on the middle of 

 that margin which lies next to its mate. That is, the auxiliary acetabu- 

 lum of a bothrium is directly opposite to that of the other bothrium of 

 the same marginal pair. The edges of the bothria, while at rest, project 

 and are slighly incurved, so that the face is concave from the acetabu- 

 lum to the edge opposite, while it is convex in a line at right angles to 

 this, or, in other words, in the line which joins the two reflexed edges of 

 the bothrium. In a state of activity the bothria effect a progressive 

 movement by prolonging that part of the border which bears the aux- 

 iliary acetabula. When in this position the bothria are somewhat tri- 

 angular, the acetabulum marking the apex of an isosceles triangle, while 

 the base is thrown into about three folds. The edges of the bothria are 

 not broken or laciniate, although often folded in such a manner as to 

 present a laciniate appearauce. The edges are finely crenulate, the 

 crenulations being about .3 mm in diameter. The faces of the bothria 

 are covered with hexagonal reticulations, like the surface of a honey- 

 comb. The fibrous tissue which forms the frame- work of this reticulated 

 surface, near the edges of the bothria, rises into parallel ribs, so that 

 the outer rim of the thin, free edge of the bothrium, instead of being 



