NO. 14 MANTER : DIGENETIC TREMATODES OF FISHES 423 



Seminal vesicle ovoid, thick walled, not distinctly divided. Pars prostatica 

 fairly short, sinuous, with prostatic cells moderately developed. Ductus 

 hermaphroditicus exceedingly long with 4 regions more or less evident : 

 a long, straight posterior portion; a thinner-walled distensible portion 

 within which the sinus tube is usually coiled ; a straight, vei-y muscular 

 portion within which the sinus tube may be extended ; and a thin-walled 

 genital atrium. Vitellaria of 7 rather thick tubes, thicker terminally. 

 Small seminal receptacle present; Laurer's canal absent. Branches of 

 excretory vesicle uniting dorsal to pharynx. Type species : E. mexicanus. 



The name Elytrophallus is from elytro {= sheath) and phallus (= 

 penis). It refers to the sheathlike manner in which the sinus sac encloses 

 the sinus tube. The name mexicanus is for the locality. 



Discussion. This trematode reveals a combination of characters 

 known in several genera. The smooth body, the rather small tail appen- 

 dage, and the form of the vitellaria all suggest the genus Sterrhurus. But 

 the seminal vesicle, the tubular pars prostatica, and especially the long 

 tubular form of the sinus sac are very different from Sterrhurus. Tubo- 

 vesicula Yamaguti, 1934 has a smooth body but a larger tail, a very long 

 pars prostatica, and a short pyriform sinus sac. These differences also 

 hold for Culpenurus Srivastava, 1935, a genus which probably should be 

 considered a synonym of Tubovesicula, Lecithocladium Liihe has a long 

 slender sinus sac and a genital pore near the mouth, but it has a ringed 

 body, long tubular vitellaria, and usually a very long pars prostatica. 

 Dinurus Looss has a ringed body, long tubular vitellaria, distinctly tri- 

 partite seminal vesicle, and lacks the ventral spherical swelling of the 

 esophagus. Elytrophallus is similar to Erilepturus Woolcock, 1935 in 

 some respects, especially in the seminal vesicle and in that the ringed con- 

 dition is practically lacking in Erilepturus. Erileptuiois, however, has a 

 more posterior acetabulum, a more posterior genital pore, a different pars 

 prostatica which is preacetabular and separated from the seminal vesicle, 

 and a shorter sinus sac. The sphincters of the sinus sac figured by Wool- 

 cock seem to divide the common genital tube into somewhat similar but 

 less evident regions, as have been noted in Elytrophallus. 



Elytrophallus is perhaps most like Erilepturus. Woolcock correctly 

 minimizes the subfamily significance of cuticular plications or rings. As a 

 consequence it becomes increasingly difficult to separate the Sterrhurinae 

 from the Dinurinae. Elytrophallus is considered in the subfamily Dinuri- 

 nae chiefly because of the length of the sinus tube, the tubular pars pro- 

 statica, and the shape and position of the seminal vesicle. 



