470 REPOET OF COMMISSIONER OF FISH AND FISHERIES. [18] 



one auxiliary acetabulum on tbe anterior border. Faces of botbria with 

 a raised rim or border, which becomes more or less free, cut, or frilled 

 as tbe worm grows weak, or wben placed in fresh water or alcohol. 



Genital apertures, both male and .female, marginal. Development 

 not known. 



This genus is closely allied to Phyllobothrium Van Beneden, but differs 

 from it in having tbe botbria pediceled instead of sessile, and in the 

 absence of a distinct neck. 



Crossobothrium laciniatum bears some resemblance to Anthobothrium 

 cornucopia Van Ben., particularly in tbe shape of the segments, but 

 differs from it in having distinct auxiliary acetabula, and in having the 

 segments begin immediately behind the head. The botbria are not so 

 long-pediceled as in A. cornucopia. The botbria, especially in living 

 specimens in sea-water, bear a superficial resemblance to Orygmato- 

 bothrium versatile Dies. (Anthobothrium musteli Van Ben.), but there is 

 no trace of a second auxiliary acetabulum on the face of the botbria. 

 The habit of the strobile is, furthermore, quite different from 0. versatile 

 Dies. 



Crossobothrium laciniatum, gen. et sp. nov. 



[Plate III, Figs. 4-18.] 



Body articulated, slightly flattened; cross-section. of segments near 

 head quadrangular; ratio of thickness to breadth about 1 to 2. The seg- 

 ments begin immediately behind the head, each is characterized by 

 having four marginal flaps on the posterior border. The anterior seg- 

 ments in the larger specimens, for a distance of 20 or 30 mm back of the 

 head, are about as broad as long, the posterior angles projecting into 

 prominent triangular flaps, which, in a few cases, stand out almost at 

 right angles to the face of tbe segment's, but are usually appressed. 

 The bodies of the segments are translucent, the posterior borders and 

 projecting flaps opaque and ivory white in color. This feature is espe- 

 cially noticeable in specimens which have lain a few minutes in fresh 

 water. Behind these slender anterior segments the remaining segments 

 increase in breadth without increasing in length. Near the middle of 

 the strobile the ratio of length to breadth is about 2 to 9. The median 

 segments are flat and the triangular flaps develop into broad, rounded 

 lobes. These lobes form a free border, which is sometimes reflexed and 

 usually emargiuate on the lateral edge. 



The posterior segments are considerably lengthened; length about 

 1.5 mm ; breadth about 2 imn , flattened ; outline usually rounded or waving, 

 narrower in front than behind, emargiuate on lateral edge. (Plate III, 

 Figs. 7, 8.) The shape of the free proglottides varies greatly while they 

 are living, but at rest or in alcoholic specimens it is quite uniform. 



The posterolateral border is profoundly emargiuate; the outline of 

 the margin concave behind, then convex throughout the greater part of 

 the length, concave again near the anterior end, which is extended into 



