Helminth Fauna of the Dry Tortugas. ISI 
broad; breadth of body varies but little; free segments with ova very much 
elongated. The reproductive cloaca is near the posterior end of the pro- 
glottis; the vagina opens behind the cirrus pouch. The ovary is situated 
about half-way between the cirrus pouch and the posterior end of the seg- 
ment. The testes occupy the median axial region of the entire segment, 
except a short space at the anterior end. The vitellaria lie along the mar- 
gins, and also spread peripherally over the median axial region, thus obscur- 
ing the other organs, especially in the mature segments. The uterus lies 
along the median line, and, in one of the free segments, extended as a 
slender tube containing ova, at least as far forward as the anterior third. 
In others the ova lay in an elongated mass from just in front of the repro- 
ductive cloaca to about the anterior fifth. 
The lateral vessels are very conspicuous, except in the free segments, 
also the last segment in the strobiles examined did not have as conspicuous 
lateral vessels as the preceding segments. 
Living specimens not seen. 
Dimensions, in millimeters: Length of longest about 30; length of head 
and neck 1.12; head, length 0.45, breadth 0.40; bothrium, length 0.45, 
breadth (estimated) 0.40; breadth of neck, anterior 0.24, base 0.27; bulbs, 
length 0.32, breadth 0.11; breadth of body near neck 0.16; distance to first 
distinct segment 0.3; first segment, length 0.03, breadth 0.16; a middle seg- 
ment, length 1.20, breadth 0.19; last segment, length 3.68, breadth 0.32; 
proboscis, length (estimated) 1, diameter, behind and in front of bulbous 
enlargement, 0.04, at bulbous enlargement 0.06. In a strobile 18 mm. long, 
the last segment was 2.24 long and 0.4 broad; the last segment in another 
of 26 mm. in length was 4 mm. long and 0.3 mm. broad. A free segment 
measured 5.5 in length and 0.6 in breadth. 
Mature segments resembling these have been noticed before in the chyle 
of the spiral valve of the tiger-shark at Woods Hole, but this is the first time 
I have seen the scoleces. 
From spiral valve of tiger-shark (Galeocerdo tigrinus), captured June 2. 
Eighty-five specimens were collected, all filiform, with a conspicuous enlarge- 
ment at the base of the proboscides and edges of the bothria folded as if 
rather thin and flexible. 
For remarks on the identification of the host see under Thysanocephalum 
(pp. 164, 167). 
23. Rhynchobothrium binuncum sp. nov. 
(Plate 8, figs. 55-64.) 
Strobile small, slender, with few segments. Bothria short, rather widely 
separated in front, at least when compressed; neck relatively long, with very 
long, slender, contractile bulbs, equaling in length half the total length of 
the head and neck; sheaths in loose spirals; proboscides long and for the 
most part with small, slender spines, but with a few larger spines near the 
