Helminth Fauna of the Dry Tortugas. 179 
that very gradually. First distinct segments begin a short distance back 
of neck, at first much broader than long, soon becoming squarish, then 
longer than broad, all with crenulate margins. Genital aperture marginal 
in a deep rounded notch at about the posterior third; ripe segments with 
ova not seen; longest segment two and one-half times as long as broad. 
There are many points of resemblance between this species and R. 
longicorne. Length of living specimens as much as 30 mm.; of alcoholic 
specimens 18 to 20 mm. 
Dimensions, in balsam, given in millimeters: Length 20; length of head 
and neck 3.28; bothrium, length 0.27, breadth 0.27; diameter of neck, ante- 
rior 0.23, posterior 0.40; bulbs, length 1.36, breadth 0.14; first distinct seg- 
ment, length about 0.08, breadth 0.40; last segment, length 1.12, breadth 
0.56; proboscis, length (estimated) 2.5; diameter at base 0.05, near distal 
end 0.03; length of longest hooks 0.017. 
The segments, in this specimen, are twenty in number, and are somewhat 
irregular in length, the last one not being the longest. The longest segment 
measures 1.6 in length, and 0.67 in breadth. 
From the nurse-shark (Ginglimostoma cirratum). 
July 6, four. July 15, seven and fragments. 
21. Rhynchobothrium curtum sp. nov. 
(Plate 6, figs. 44-47.) 
Bothria broad-elliptical or oval-elliptical and somewhat thick, placed on 
the sides of the head which correspond to the lateral margins of the strobile. 
Head, in side view, heart-shaped; neck very short, shorter than bcthria; 
bulbs oval-elliptical, sheaths nearly straight; proboscides short, hooks small. 
Body at first a little narrower than neck; first segments begin near neck, at 
first much broader than long, but soon becoming as long as broad, then very 
soon becoming longer than broad, with rounded corners and more or less 
crenulated or indented margins; marginal vessels conspicuous ; reproductive 
aperture at about the posterior fourth. 
Only preserved specimens were seen; the largest specimen noted meas- 
ured 10 mm. in length. 
Measurements, in millimeters, of a specimen mounted in balsam: Length 
6; head, length 0.21, breadth 0.22; neck, length 0.06, breadth 0.07; breadth 
of body behind neck 0.10; distance to first distinct segment 0.08; first seg- 
ment, length 0.02, breadth 0.11. 
The hooks were not seen very distinctly, as no proboscis was everted. 
A number of measurements showed that the longer hooks were about 0.024 
in length. Only one was found which measured as much as 0.04. It was 
near the base of the proboscis. 
As the increase in length and breadth of segments is much the same in 
different specimens, the following measurements of all the segments in one 
example are given: 
