DIGENETIC TREMATODES — MANTER AND VAN CLEAVE 321 



ably smaller than the sizes originally given for O. sphaericus but 

 not smaller than 0. sebastodis. Unfortunately, in 0. adsphaericus 

 the extent of the vitelline follicles is unreliable as a diagnostic aid, 

 since both their anterior extent and their interruption opposite 

 the testes varied in our material. However, in O. adsphaericus the 

 follicles are almost always interrupted opposite the testes, whereas 

 Ozaki states (1928, p. 12) that in O. sphaericus they are usually 

 continuous but may be discontinuous opposite the gonads. 



A series of 11 specimens of Opecoelus from the intestine of 

 Girella nigricans (Ayres) showed some fairly consistent differ- 

 ences from those taken from Clinocottus. In individuals from 

 Girella the pharynx was often somewhat larger, with reference to 

 diameter of the oral sucker, than was typical for individuals 

 from Clinocottus; likewise the eggs averaged larger, and the oral 

 papillae were in some instances longer and more pointed. How- 

 ever, in some individuals from Girella, measurements of these de- 

 tails fell distinctly within the range established for the series from 

 Clinocottus. Consequently it seems admissible to identify the 

 specimens from Girella as Opecoelus adsphaericus and in so doing 

 to recognize considerable individual variability within this species. 



The name adsphaericus indicates the similarity of the species to 

 O. sphaericus. 



Related genera occur in the Atlantic, but as yet the genus 

 Opecoelus is reported only from Japanese waters and from the 

 American Pacific coast. 



Genus PSEUDOPECOELUS von Wicklen, 1946 



PSEUDOPECOELUS GIBBONSIAE, new species 



Plate 12, Figures 6, 7 



Description (based on two specimens). — Body (pi. 12, fig. 6) 

 rather thick, unspined, 2.262 to 2.558 mm. in length, 0.643 to 0.780 

 mm. in thickness at acetabular level. Oral sucker (os) 0.179 to 

 0.195 mm. in length; 0.187 to 0.195 mm. in thickness. Acetabulum 

 (ac) slightly protuberant, without papillae; 0.421 to 0.468 mm. in 

 length ; 0.382 to 0.429 mm. in depth. Ratio of sucker lengths, 1 :2.35 

 to 2.4. Acetabulum 0.773 to 0.811 mm. or about one-third body 

 length from anterior end. Prepharynx 0.055 to 0.086 mm. in length. 

 Pharynx (ph) large, 0.163 to 0.179 mm. long by 0.179 to 0.195 mm. 

 thick. Esophagus frequently longer than pharynx, 0.269 mm. long 

 in the 2.558 mm. specimen, in which the pharynx was 0.179 mm. 

 long. Ceca (ic) ending blindly near posterior end of body. Genital 

 pore (gp) ventral, slightly to the left, opposite posterior fourth 

 of pharynx; accessory suckers lacking. Testes (t) smooth, sub- 

 spherical, tandem, contiguous, in midregion of hindbody; post- 



