74 Papers from the Marine Biological Laboratory at. Tortugas. 



SIPHODERID^. 



Siphodera (gen. nov.) vinaledwardsii (Linton). (Figs. 208, 209a.) 



Monostomum vinaldwardsii, Linton, Bull. U. S. Fish Commission 1899, p. 

 470, figs. 373-376; Bull. Bureau of Fisheries, vol. xxiv, 1904, p. 370 and 

 410'; Proc. Nat. Mus., xxxn, p. 118, fig. 97. 



Etymology: trtywv, a tube; 8 1 py, neck. 



Two trematodes from Ocyurus chrysurus appear to belong to this 

 species. The most striking difference between them and specimens from 

 Opsanus tau and from Ocyurus chrysurus in Bermuda is in the character 

 of the testes. The right testes agree with the descriptions already pub- 

 lished, but on the left side instead of 4 or 5 testes there is but 1. Until 

 the limits of variability are better known it does not seem advisable to 

 place this form in a new species. 



In order to compare this with specimens in my collection, and at the 

 same time taking advantage of the opportunity thus afforded to revise 

 the description of the species, I made sections of old material and there- 

 fore can make a few needed emendations and corrections in the original 

 description. I am still obliged to leave one point in the anatomy not 

 entirely cleared up, viz., the real nature of the tube-like structures in 

 the neck. 



EMENDED DESCRIPTION OF THE SPECIES. 



Body thickish, depressed, slightly convex above, flat below, outline 

 varying, but approximately ovate, covered with exceedingly minute 

 villous spines. Oral sucker circular, subterminal, the aperture nearly 

 circular. Pharynx varying in preserved specimens, subglobular in life, 

 near oral sucker but in favorable positions it is preceded by a short 

 prepharynx. Esophagus short; intestinal rami extending to posterior 

 end of body. The ventral sucker is a part of the genital apparatus 

 (cirrus) and is depressed in a circular pit of the body-wall. The border 

 of this pit is muscular and has strong, muscular fibers radiating from it. 

 Contiguous with the genital sucker, dorsal or a little in front of it, is 

 a muscular, subglobular portion lined with coarse, wedge-like masses 

 resembling the lining of the prostatic portion of the cirrus-pouch in many 

 of the distomes figured in this paper. Since this portion is surrounded 

 by a few cells which appear to be prostate cells, this is doubtless the real 

 nature of the structure. This portion is followed by a tubular seminal 

 vesicle with muscular walls. Towards its posterior end it is more or less 

 convoluted. On the right side of the undoubted seminal vesicle is a larger, 

 oval seminal vessel, which is probably the seminal receptacle, although 

 of this I am not quite certain. Posteriorly it lies dorsal to the ovary. 

 A structure which appears to be Laurer's canal was noted in one set of 

 sections. Testes variable, but usually 4 or 5 on each side. They begin 

 from about the middle of the length to the posterior third and extend 

 from the point of beginning approximately half-way to the posterior 

 end. The ovary is many-lobed and situated on the median line a short 

 distance behind the genital sucker, from which it is separated by the 

 seminal vesicle. The vitelline glands in the older specimens are confined 

 mainlv to the lateral regions of the middle third of the body ; in younger 



