50 BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



nearly circular and limited by a cutinous (chitinous) ring. Spicules 

 equal or unequal. Gubernaculum present or absent. 

 Type-genus. — Heterakis Dujardin, 1845. 



1. Esophageal bulb lacking; caudal alae feebly developed Ascaridia, p. 77. 



Esophageal bulb present ; caudal alae well developed 2. 



2. Head with " cordons " consisting of tubular grooves- Pseudaspidodera. p. 102. 

 Head without " cordons " Heterakis. p. 50. 



Genus HETERAKIS Dujardin, 1845 



Sj/nonijms. — Heteracis Molin, 1858; Ganguleterakis Lane, 1911. 



Generic diagnosis. — Heterahinae (p. 49) : Mouth with 3 lips. 

 Esophagus subcylindrical, progressively swollen toward its posterior 

 extremity and with a distinct bulb. Two lateral membranes present 

 or absent. Males with caudal alae well developed and sustained by 

 papillae of ray-like appearance. Spicules equal, subequal, or unequal, 

 without accessory piece. Preanal sucker with a distinct cutinous 

 (chitinous) ring. Females with vulva toward the middle of the 

 body, the uterine branches passing in opposite directions. Eggs with 

 thick shell. 



Parasitic in intestines (especially the ceca) of birds, mammals, and 

 reptiles. 



Type-species. — Heterakis gallinae (Gmelin, 1790) Freeborn, 1923 

 ( =H. vesicularis ) . 



KEY TO SPECIES OF HETERAKIS 



1. Description incomplete; from Ciconict (Euxenura) rttagitari. 



Heterakis valdenmcroiiata, p. 74. 

 From other hosts than above 2 



2. Male with not more than 9 pairs of caudal papillae ?>. 



Male with more than 9 pairs of caudal papillae 4. 



3. Male with 6 pairs of caudal papillae; sucker 35/u anterior to elo'aeal aperture: 



tail of female 1/6:8 of total length Heterakis bancrofti, p. 50. 



Male with 9 pairs of caudal papillae; sucker 194,ot anterior to cloacal aper- 

 ture; tail of female 1/14 of total body length_ Heterakis chenonettae, p. 60. 



4. Spicules unequal 5. 



Spicules equal or subequal (not more than r>0,u difference in their lengths ) _ 13. 



5. Longer spicule over 1 mm. in length 6 



Longer spicule less than 1 mm. in length 12 



6. Longer spicule over 2 mm. in length 7. 



Longer spicule less than 2 mm. in length 10. 



7. Short spicule 640/x long Heterakis parisi, p. 69. 



Short spicule 700/t or longer 8. 



S. Tail short in both sexes, the anus of female being 780^, the cloacal aperture 



of male 170fi, from posterior end Heterakis valvata, p. 74. 



Tail long compared with above, the anus of female being not less than 9SS,u. 



the cloacal aperture of male not less than 416/i, from posterior end 9. 



9. Preanal sucker 60 to 75/* in diameter; right spicule 2 to 2.17 mm. long; 

 female JO to in mm. long; eggd 03 to Tin I6og in 38 to !S,u wide. 



Heterakis gallinae, p. 52. 



