I7J 



Papers from the Marine Biological Laboratory at Tortugas. 



with strong longitudinal muscle bundles of relatively coarse strands. Stro- 

 bile, so far as certainly seen, filiform. First distinct segments about as long 

 as broad, nearly circular, so that the first five, in one specimen, made a 

 moniliform portion of the strobile ; succeeding segments rod-shape, very 

 much longer than broad, and rather loosely attached, margins finely crenate. 

 Details of the anatomy were not certainly made out for ripe segments, but 

 are probably much like those of P. brevispine. The two species may be 

 distinguished from each other by means of the hooks, which present quite 

 marked differences besides that of size. 



From the nurse-shark (Ghigliostoina cirratuni}, July 2, two; July 5, six. 

 All small, with no mature segments. 



Dimensions of living specimen in millimeters: Head, length 0.35, breadth 

 0.35 ; bothria, length 0.35, breadth 0.21 ; length of hooks, base not included, 

 larger 0.06, smaller 0.03 ; diameter of neck 0.09 ; distance to first distinct 

 segment 0.42; first segment, length 0.07, breadth o.o/ ; number of segments 

 9 : last segment, length 0.63, breadth 0.06. In two mounted specimens the 

 length of the bothrium in each was 0.35, and the hooks, including the base, 

 0.15. 



12. Pedibothrium brevispine gen. et sp. nov. 

 (Plate 3, figs. 20-22; plate 4, figs. 23-25.) 



ilothria much as in P. lougispine, except that, in the alcoholic specimens 

 at least, they project farther in front of the hooks, and the free margins 

 of the bothria are perhaps wider. The hooks are much smaller than those 

 of P. lougispine, and the prongs are unequal and unequally curved. The 

 outer prong of each pair is curved much as in that species, but the inner 

 prong is nearly straight and abruptly enlarged at the base. The common 

 base of the two prongs of a hook is irregularly triangular. Neck distinct, 

 with very conspicuous muscle bands, and is minutely spinose. 



There appears to be a considerable variety in the strobiles, some being 

 short, with relatively few segments, others longer, with many immature seg- 

 ments. In the longer strobiles the last segments are no farther advanced 

 in the development of the reproductive organs than those on the shorter 

 strobiles. 



The first segments broader than long, and, especially in the shorter type 

 of strobile, have a tendency to become moniliform. Later they are much 

 elongated, becoming six or more times as long as broad. The free segments 

 are long-fusiform, eight or more times as long as broad, the posterior end 

 being the more slender. The vagina and cirrus have their common aperture 

 on the margin a little behind the middle. The vagina opens in front of the 

 cirrus, proceeds almost at right angles to the long axis of the segment to 

 (lie median line, then turns almost at right angles and passes near the median 

 line to the ovaries. The ovaries are paired and lobed organs and lie nearly 

 hall -way between the reproductive cloaca and the posterior end. The vitel- 



