NO. 14 MANTER : DIGENETIC TREMATODES OF FISHES 339 



left side almost always extending farther back than those on the right, 

 often reaching to anterior testis; number of follicles 11 to 17 on each 

 side. Uterus, chiefly in transverse coils, fills most of body, extending 

 anterior to vitellaria, in extended specimens reaching almost to anterior 

 sucker; inverted sucker pushing against uterus. Uterus not extending 

 posterior to genital pore. Eggs large, j^ellow brown, rather thick shelled, 

 tapering slightly toward anterior end, 22 to 26 by 12 to 15 /x, most eggs 

 about 24 by 14 /x. Excretory vesicle extending slightly anterior to ovary 

 but not anterior to vitellaria. 



The name introversus is given to indicate the striking characteristic 

 of inversion of the anterior end. 



Comparisons. No other species of Bucephalus exhibits the inversion 

 of the anterior end. The stomach of the host is an unusual location for 

 a gasterostome, most of which occur in the intestine. Manter (1931) has 

 previously recorded a gasterostome from the gills of a fish, and one speci- 

 men of B. introversus was found on the gills. However, the gills prob- 

 ably are not a normal place for these parasites which more likely wan- 

 dered up from the stomach after death of the host. 



B, uranoscopi is more elongate, with two processes on the tentacle; 

 its uterus does not extend so far anteriorly; and the eggs are smaller. 

 B. kathetostomae (Manter) has an anterior sucker of similar structure 

 but has an entirely different shape; the vitellaria, uterus, and mouth 

 have different positions, and the eggs are smaller. B. polymorphus seems 

 to be most similar but is less elongate, the vitellaria are more anterior, 

 the cirrus sac shorter. B. various differs in form of anterior sucker, in 

 egg size, and in genital lobes. 



Prosorhynchus ozakii Manter, 1934 

 (Plate 33, fig. 13) 



Hosts and Localities: 



1. An unidentified, spotted, grouperlike fish from Isabel 

 Island, Mexico 



2. Mycteroperca olfax ( Jenyns) from Albemarle Island, 

 Galapagos 



3. Mycteroperca xenarcha Jordan from Albemarle Island, 

 Galapagos 



Location: Ceca 



Number: One to several specimens in a host 



The Mexican material had eggs 26 to 29 by 14 to 19 ju, while the 

 Galapagos specimens (from Mycteroperca olfax and M. xenarcha) had 



