8 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 79 : aut. 26 



The worm measures 5 mm. by 2 mm. The mouth sucker is large, 

 with its margin projected forward in the middle and at each side. 

 It is lined with minute teeth, or spicules. The pharynx is small and 

 opens into the intestinal ceca, which are conspicuous from being 

 filled with black pigment, which extends into the branches in the 

 appendix and the fixation disk. 



The genital pore lies just behind the bifurcation of the intestine. 

 The uterus contains 8 or 10 eggs, which are fusiform and measure 

 144/A by 48/A. The}^ have a long fine filament at each end. The 

 penis is long and cylindrical and undulates to the point where it 

 connects with a thick-walled seminal vesicle, which in turn receives 

 the vas deferens. The testis forms a finely lobulated mass in the 

 posterior part of the body. 



The vaginal orifices lie at the level of the genital orifice, just inside 

 the bend of the intestinal ceca. The vaginae are broad, convoluted, 

 and run back separately to the vitelline duct. There is a rather 

 distinct ootype, although the anterior part of the uterus is so greatly 

 distended. The ovary is lobulated and folded on itself, and there 

 is a large receptaculum seminis filled with spermatozoa. 



The suckers of the fixation disk are very large ; the hooks measure 

 320/A from tip to tip and SCO^u, over all (fig. 1, a). The whole lining 

 shows a fine roughening with tiny spicules. The small booklets have 

 a broad base with very slight depression between the two rootlets 

 and with a bend or elbow in the shank of the hook (fig. 1, a'). This 

 is not quite so marked in these specimens as Cerfontaine described 

 it, but it is quite visible. Nor are the large hooks of the suckers 

 smaller in these specimens than in S. vulgaris — indeed these are the 

 largest we have encountered. Still the agreement seems so close 

 that we have little hesitation in believing that this is really jS. cams. 



Specimens examined. — U. S. N. M. Helm. Coll. No. 8139-8140. 



LITERATURE CITED 

 CATJSEry, David. 



1926. Onoliocotyle somniosi n. sp., an ectoparasitic trematode of the sleeper 

 shark (Soinviosus microcephalus) . Parasitology, vol. 18, no. 2, 

 pp. 195-202, 4 figs., 1 pi. 

 Cerfontaine, Paul. 



1900. Contribution a I'etude des Oetocotylid<5s. V. Les Onchotylinae. Arch, 

 (le Biol., vol. 16, pp. 345-^78, 4 pis. 

 Lebouk, Marie V. 



1907. The mussel beds of Northumberland. Northumberland Sea Fisheries 

 Committee, Report on the Scientific Investigations for the Year 

 1906, pp. 28-46, 6 maps. 



VAN BENEDEN, p. J. 



1858, Memoire sur les vers intestinaux. Extrait du supplement aux 

 Comptes Rendus de I'Acaderaie des Sciences, vol. 2. Paris. 



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