176 Papers from the Marine Biological Laboratory at Tortugas. 
17. Rhynchobothrium speciosum Linton. 
(Plate 11, figs. 78, 79.) 
Proc. U. S. Nat. Mus., vol. x1x, pp. 801-805, plate Lxiv, figs. 13, 14, and plate 
LXV, figs, 1-7. Bull. U.S. F. C., 1800, p. 413, etc., noted tn 11 hosts: “Bull 
Bureau of Fisheries, vol. xxiv, pp. 360, 373, 384. 
This species is comparatively easy to recognize on account of the highly 
characteristic arrangement of the hooks. The encysted stage only was 
found. The following notes were made at the time of collecting: 
1. Epinephelus striatus. 
July 7.Elongated cysts, colored with brown pigment, were found on 
the liver and mesentery. They were left over night in sea-water, and on 
the following morning five larve had crept out of the cysts. 
July 11, several; July 12, two. Long-pyriform cysts with dark pigment 
were found on the viscera. The blastocysts (plerocerca) were very active 
after they had been freed from their cysts. 
Dimensions of a living larva, in millimeters: Length 40; breadth, varying 
with the length, about 1 when the length was 40; length of head and neck 7; 
length of bothria 0.84; breadth of head, flattened, 1.12; diameter of neck, 
flattened, anterior 0.77, at bulbs 0.84; contractile bulbs, length 1.40, breadth 
0.143; proboscis, length 3.5, diameter, near base, exclusive of hooks, 0.068. 
There is much variety of size and shape of bothria and neck in the alco- 
holic specimens. 
Many cysts, dark-brown and filled with waxy degenerate tissue, were 
found in the stomach wall of the grouper on July 7 and 8, some of which 
may be due to this parasite. 
2. Mycteroperca venenosa. 
July 18.—Many elongated cysts were found on the viscera. These cysts 
were all very dark-brown, some of them even almost blue-black. One larva 
was released and proved to belong to this species. 
3. Mycteroperca bonaci. 
July 11.—Several large, long-pyriform cysts were found on the viscera. 
Most of these cysts were dark-brown, slightly iridescent, and associated 
with mats or tangles of filiform cysts which had been occupied by imma- 
ture nematodes. 
A small larva from this lot was thought at the time of collecting to be 
specifically different from the larger specimens, but after mounting the worm 
in balsam and studying the hooks, I have concluded to record it under this 
species. While it is much smaller than the others, the arrangement of the 
hooks is in close agreement. 
Diameter of proboscis, exclusive of hooks, in millimeters, 0.04; length 
of largest hooks 0.021, as against 0.05, the usual size. 
