530 PROCEEDINGS OF TEE NATIONAL MUSEUM. vol. 57. 



Genus HETEROPHYES Cobbold, 1866. 



Generic diagnosis. — Heterophyidae : Cuticiilar scales rectangular, 

 longer than broad, length about 5 to 7.5 [i. Prepharynx short, 

 pharynx nearer to the oral sucker than to the bifurcation of the in- 

 testine. Intestinal ceca extend into the posterior portion of the body 

 reaching the level of or extending behind the testes. Ventral sucker 

 median near the middle of the body. Genital pore surrounded by a 

 genital sucker located near the ventral sucker at one side or obliquely 

 behind it. Genital sucker armed with a circlet of curved chitinous 

 rodlets, 25 to 80 in number ; circlet more or less discontinuous on the 

 side of the genital sucker toward the ventral sucker; rodlets about 

 .10 to 20 [X long, with about 5 minute pointed processes in a row along 

 the convex side. Testes globular or oval, situated side by side near 

 the posterior end of the body right and left of the median line. 

 Seminal vesicle well developed, U-shaped, behind the genital sucker. 

 Ovary globular or ovoid, situated in front of the testes, median, or on 

 the right of the median line. Seminal receptacle between testes 

 and ovary. Vitellaria in the lateral fields in the posterior end of the 

 body near the dorsal surface, not extending forward much beyond 

 the level of the anterior border of the ovary. Coils of uterus in the 

 region between the testes and the ventral sucker, none in front of 

 the latter. 



Type species. — Heterophyes aegyptiaca Cobbold, 1866 {=Distoma 

 keterophyes Siebold, 1852, renamed). 



The flukes of the genus Heterophyes in all probability occur in 

 their immature stages in fish, the adults having been found thus far 

 only in fish-eating birds and mammals, including man, this opinion 

 being based on the fact that related flukes in the family Heter- 

 ophyidae are known to have immature stages in fish. 



It appears questionable whether all of the species of Heterophyes 

 that have been described are really distinct, but the writer has fol- 

 lowed Looss (1902n) in recognizing seven species. It seems not un- 

 likely, however, that Looss has carried the process of separating 

 species beyond the limits of practicability and it is doubtful whether 

 some of the species described by him can readily be distinguished 

 from others, at least in the case of individual specimens. 



KEY TO SPECIES. 



1. Length 3 mm. or more ; vitellaria dorsally extend- 



ing inwards nearly to the borders of the ovary_ Hetetophyes persicus. 

 Length not over 2 mm. ; vitellaria limited to 

 lateral fields 2. 



2. Length usually greater than 0.9 mm. ; vitellaria 



with about 14 lobules in each lateral field ex- 

 tend as far forward as the level of the anterior 



