No. 2322. TREMATODE FAMILY HETEROPHYIDAE— RANSOM. 529 



tatic cells, and extending from the anterior limb of the seminal ves- 

 icle to the genital opening. Ovary oval, globular, or slightly lobed, 

 median, or usually on the right, rarely on the left, of the median line, 

 anterior of the testes. Seminal receptacle and Laurer's canal pres- 

 ent, near the ovary, usually in relation with its posterior border. 

 Vitellaria, located mainly in the lateral fields in the posterior end of 

 the body, may extend anteriorly to or a short distance beyond the 

 level of the ventral sucker, and may enter the median field and 

 approach or extend to the median line in this region. Uterus ar- 

 ranged usually in a few transverse loops, but sometimes with nu- 

 merous loops, limited to the region in front of the testes and behind 

 the genital pore, except occasionally one or more loops may be pres- 

 ent in front of the latter. Eggs usually not very numerous, from 15 

 to 50 [JL long, rarely {Paracoenogonimus) may exceed 100 [jl in length. 

 Adults parasitic in the intestine of mammals and birds. 

 Type genus. — Heterophyes Cobbold, 1866. 



KEY TO GENERA. 



1. Eggs not over SO/i long 2. 



Eggs over 100/a long Paracoenogonimus, p. 550. 



2. Ventral sucker median 3. 



"Ventral sucker and genital pore displaced to right of median 



line Metagonimus, p. 538. 



3. Genital sucker present 4. 



Genital sucker absent 5. 



4. Genital sucker median, directly posterior of the more or less 



rudimentary ventral sucker Cryptocotyle, p. 543. 



Genital sucker at one side of or obliquely beliind the well-de- 

 veloped ventral sucker Heterophyes, p. 530, 



5. Prepharynx long, pharynx usually nearer to the bifurcation of the in- 



testine than to the oral sucker 6. 



Prepharynx short, pharynx much nearer to the oral sucker than to the bi- 

 furcation of the intestine 8. 



6. Oral cecum present Ascocotyle, p. 561. 



Oral cecum absent 7. 



7. Mouth surrounded by a crown of spines ; vitellaria extend into 



the region in front of the ventral sucker Centrocestus, p. 559. 



Mouth not surrounded by a crown of spines; vitellaria limited to 

 the region of the testes Pygidiopsis, p. 568. 



8. Vitellaria commonly extend into the median field in front of 



ventral sucker, frequently meeting in the median line, with 

 comparatively few lobules in the post-testicular region, these 

 not crossing the median line, and not extending between the 



testes Cotylophallus, p. 554. 



Vitellaria usually strictly lateral in the anterior region, not 

 extending inwards to the median line in front of the ventral 

 sucker, but with numerous lobules behind, between and 



often dorsal and ventral of the testes Apophallus, p. 551. 



144382— 20— Proc.N.M.vol.57 34 



