470 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [18] 
one auxiliary acetabulum on the anterior border. Faces of bothria with 
a raised rim or border, which becomes more or less free, cut, or frilled 
as the worm grows weak, or when placed in fresb 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 the bothria pediceled instead of sessile, and in the 
absence of a distinct neck. 
Crossobothrium laciniatum bears some resemblance to Anthobothrium 
cornucopia Van Ben., particularly in the shape of the segments, but 
differs from it in having distinct auxiliary acetabula, and in having the 
segments begin immediately behind the head. The bothria are not so 
long-pediceled as in A. cornucopia. The bothria, especially in living 
specimens in sea-water, bear a superficial resemblance to Orygmato- 
bothrium versatile Dies. (Antirobothrium musteli Van Ben.), but there is 
no trace of a second auxiliary acetabulum on the face of the bothria. 
The habit of the strobile is, furthermore, quite different from O. versatile 
Dies. 
Crossobothrium laciniatum, gen. et sp. nov. 
[Plate UI, Figs. 4-18.] 
Body articulated, slightly flattened ; cross-section of segments near 
head quadrangular; ratio of thickness to breadth about 1 to2. Theseg- 
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 50™™ 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 the segments, but are usually appressed. 
The bodies of the segments are translucent, the posterior borders and 
projecting flaps opaque aud 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 emarginate on the lateral edge. 
The posterior segments are considerably lengthened; length about 
1.5""; breadth about 2", flattened; outline usually rounded or waving, 
narrower in front than behind, emarginate on lateral edge. (Plate III, 
Figs. 7,5.) The shape of the free proglottides varies greatly while they 
are living, but at rest or in alcoholic specimens it is quite uniform. 
The postero-lateral border is profoundly emarginate; the outline of 
the margin concave behind, then convex thronghout the greater part of 
the length, concave again near the anterior end, which is extended into 
° 
an | 
Cen I 
rit aa 
