i;fi Papers from the Marine Biological Laboratory at Tortugas. 



17. Rhynchobothrium speciosum Linton. 



(Plate ii, figs. 78, 79-) 



Proc U S Nat. Mus., vol. xix, pp. 801-805, plate LXIV, figs. 13, 14, and plate 

 LXV, figs, 1-7. Bull. U. S. F. C, 1899, p. 413, etc., noted in 11 hosts. Bull. 

 Bureau of Fisheries, vol. xxiv, pp. 369, 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. Epinephelns striatus. 



j u ly 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 larvae had crept out of the cysts. 



. July u, 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 i 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 

 0.14; 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 1 8. 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 ii. 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. 



