184 Papers from the Marine Biological Laboratory at Tortugas. 
breadth 0.48; diameter of neck, anterior 0.32, posterior 0.64; bulbs, length 
0.64, breadth 0.16; first distinct segment, length, about 0.06, breadth 0.24; 
fifth segment, length 0.14, breadth 0.20; tenth segment, length 0.35, breadth 
0.24; twentieth and last segment, length 2.08, breadth 0.22; proboscis, length, 
estimated, 3, breadth, exclusive of hooks, base 0.05, near apex 0.04; length of 
longest hooks, base 0.035, at apex of everted part, about 0.6 from base, 0.028. 
From spiral valve of nurse-shark (Ginglimostoma cirratum), July 6, one. 
ENCYSTED STAGE, 
(Plate 10, fig. 75, and plate 11, figs. 76, 77.) 
A larva taken from a cyst in the walls of the rectum of the green moray 
(Lycodontis funebris) is in such close agreement with this species that I 
do not hesitate to place them together. 
The blastocyst resembles that of the genus Synbothrium. Its posterior 
end was orange-yellow, which perhaps has no special significance. 
Dimensions, in millimeters, of living larva, flattened: Length 4.34; both- 
rium, length 0.75, breadth 0.75; neck, length 3.16, breadth 0.47; bulbs. 
length 0.63, breadth 0.16; proboscis, length, estimated, 1.96, diameter, ex- 
clusive of hooks, 0.056; length of longest hooks 0.035. 
26. Rhynchobothrium sp. 
(Plate 11, figs. 80-82.) 
A single minute tetrarhynch, found July 12, in the spiral valve of a 
large cub-shark (Dasyatis say), has many points of resemblance to R. 
hispidum, but the hooks, while showing close relationship, are not in suff- 
ciently close agreement to permit the specimen to be referred with certainty 
to that species. Only the head and neck and a very short piece of the 
strobile were secured. 
The bothria are separated by a space at the anterior ends, and are widely 
divergent at their posterior ends. The neck is nearly linear, only slightly 
larger at base than in front, and is spinose. The bulbs are parailel and 
equal to about half the length of the neck; sheaths loosely spiral ; proboscides 
relatively long; hooks very small, for the most part slender and spinose, a 
few larger hooks, broad, in lateral view, near the base. Only the basal por- 
tion of the proboscides was seen. The hooks on the inverted portion do 
not show much variety. None of the broad variety, seen near the base, and 
characteristic of R. hispidum, could be made out through the transparent 
walls of the sheaths. 
Dimensions, in millimeters, of specimen mounted in balsam: Length of 
head and neck 0.72; length of bothrium 0.19; bulbs, length 0.32, breadth 
0.04; diameter of proboscis, exclusive of hooks, 0.017; length of iargest 
hooks 0.007. 
