NO. 14 MANTER : DIGENETIC TREMATODES OF FISHES 357 



Localities: Socorro and Clarion islands, Mexico, (type lo- 

 cality) — in B. poly le pis 

 Charles Island, Galapagos 

 Isabel Island, Mexico, — in B. verres 



Number: Few to many present in 2 specimens of each host 



SPECIFIC DIAGNOSIS OF PSEUDOCREADIUM SCAPHOSOMUM 



Body flat and thin, subcircular, with very thin inrolled edges giving 

 it a bowllike appearance; edges (when flattened by pressure) more or 

 less frilled; cuticula smooth except for a few spines seen near the an- 

 terior end of some specimens. Probably a few easily lost spines are nor- 

 mally present. The body may be somewhat longer than wide or wider 

 than long; length 1.552 to 2.268; width (at midbody level) 1.620 to 

 2.078 (specimens from B. verres somewhat smaller). Oral sucker sub- 

 terminal, subcircular, 0.112 to 0.165 in diameter; acetabulum just an- 

 terior to midbody, only slightly larger than oral sucker, 0.165 to 0.195 

 in diameter. Forebody 0.675 to 0.937. Pharynx 0.068 to 0.102 long by 

 0.058 to 0.097 wide; esophagus long and narrow, almost as long as 

 pharynx; ceca conspicuous, undulating, diagonally diverging backward, 

 then bowed, some distance from edges of body, tips converging and al- 

 most meeting before ending blindly well anterior to posterior enA of 

 body. The ceca thus arch around a central area containing most of the 

 reproductive organs. Excretory pore dorsal, median, between tips of ceca ; 

 excretory vesicle extending, dorsal to uterus, to near acetabulum where 

 it gives off an anterior and a posterior pair of tubules. 



Genital pore slightly to the left, opposite posterior end of esophagus. 

 Testes symmetrical, immediately posterior to acetabulum, smooth or 

 slightly irregular in outline, intercecal, separated by ovary. Cirrus sac 

 (fig. 29) large, claviform, extending from genital pore diagonally back- 

 ward, overlapping anterior half of acetabulum. In its base is a small, 

 transversely extended, ovoid seminal vesicle followed by a large bipartite 

 prostatic vesicle. Posterior portion of prostatic vesicle larger and more 

 elongate, connected by a posteriorly directed, narrow duct with the more 

 spherical anterior portion. Basal portion of cirrus papillated, filling most 

 of the anterior half of the sac, making one backward loop, anterior por- 

 tion smooth, muscular. Genital atrium short. External seminal vesicle 

 present, short, tubular, little coiled. Prostate gland large, entirely ex- 

 ternal, surrounding most of cirrus sac. Ovary more or less lobed, median, 

 intertesticular, im.mediately postacetabular. Vitellaria of small follicles 



