Genus SchistofcMs — Hanson 
449 
rior to acetabulum; both ends slightly tapered. 
Rows of widely spaced, short, blunt spines 
rarely extend as far posterior as acetabulum. 
Ventrally spines somewhat heavier and extend 
more posteriorly. Traces of eye-spot pig- 
ment present. Oral sucker subterminal, 0.161 
to 0.300 mm. long, 0.175 to 0.315 mm. wide, 
very nearly round. Acetabulum 1/4 to 1/5 
body length from anterior end; 0.117 to 0.234 
mm. long by 0.119 to 0.234 mm. wide, very 
nearly round; sucker ratio 1:0.530 to 1:0.801. 
Prepharynx very short, appearing absent in 
many specimens; pharynx rounded, 0.080 to 
0.146 mm. long by 0.098 to 0.169 mm. wide; 
esophagus 0.029 to 0.131 mm. long; bifurca- 
tion immediately anterior to acetabulum; area 
of bifurcation voluminous; ceca parallel to 
body walls, each terminating in anus; ani 
terminal, each encircled with cuticular furl. 
Genital pore median or slightly to left of 
median line, at anterior border of acetabulum. 
Testes 11, intercecal, serial and contiguous; 
0.044 to 0.190 mm. long by 0.060 to 0.208 
mm. wide, anterior testes usually larger than 
posterior. Pattern of vasa efferentia varied. 
Usually a single vas efferens from each testis 
leading to a vas deferens; in some instances 
two vasa efferentia arise from a common 
origin on a testis (Fig. lb). Two vasa defer- 
entia just median to ceca enter posterior por- 
tion of seminal vesicle separately. Seminal 
vesicle bipartite; posterior portion 0.095 to 
0.354 mm. long by 0.085 to 0.248 mm. wide, 
rounded, extending posteriorly from level of 
mid-acetabulum, never reaching ovary, joined 
to anterior portion by a short, narrow tube; 
anterior portion much smaller than posterior, 
longer than wide, variable in size, opening 
into genital sinus with uterus. Prostatic cells 
loosely surround anterior portion of seminal 
vesicle. Ovary round, 0.073 to 0.162 mm. 
long by 0.080 to 0.162 mm. wide, lying to 
right of median line just anterior to anterior 
testis, but never touching it. Uterus with 3 
or 4 intercecal coils; entering genital sinus 
dorsal to acetabulum (Fig. Ic). Uterus always 
extends posteriorly at least to anterior margin 
Fig. 1. Schistorchis stenosoma Itom Cantherims pardalis 
(Ruppell), file fish, a, Ventral view; b, pattern of vasa 
efferentia and vasa deferentia (diagrammatic); c, ter- 
minal genital ducts (ventral view); <7, ootype region 
(dorsal view), a, c, and d drawn with the aid of a camera 
lucida. Projected scale in millimeters. Abbreviations: 
a — anus, e = egg, ev ~ excretory vesicle, gp = genital 
pore, gs = genital sinus, Ic — Laurer’s Canal, mg = 
Mehlis’ gland, ov = ovary, sr = seminal receptacle, 
sv = seminal vesicle, / = testis, ut = uterus. 
of ovary, usually to posterior margin of ovary, 
occasionally slightly beyond ovary although 
never reaching anterior testis. Mehlis’ gland 
dorsal to ovary, diffuse, extending from an- 
terior edge of anterior testis to level of mid- 
ovary, intercecal. Laurer’s canal well devel- 
oped, opening midway between acetabulum 
and ovary, dorsal to left cecum; a short, nar- 
row tube directed first medianly and then 
posteriorly, enlarging into receptacle-like por- 
