52 BULLETIN 110, UNITED STATES NATIONAL MUSEUM 



21. Male with cloacal aperture 270/t from posterior end ; preanal sucker 180/x in 



diameter ; spicules 630 to 650/* long ; female with anus 460/t from posterior 



end ; vulva at anterior third of body Heterakis alata, p. 55. 



Male with cloacal aperture 420/x from posterior end ; preanal sucker 230/x in 

 diameter ; spicules 850/t long ; female with anus 220/t from posterior end ; 

 vulva at about anterior fifth of body Heterakis skrjabini, p. 71. 



22. Tail of male 1/2S of total body length ; preanal sucker 90/t in diameter ; 10 



pairs of caudal papillae Heterakis psophiae, p. 69. 



Tail of male 1/55 of total body length ; preanal sucker very promi- 

 nent, 220/* iu diameter; 8 pairs of caudal papillae. 



Heterakis papillosa, p. 67. 



23. Female not over 7.6 mm. long 24. 



Female 11.6 mm. to 34 mm. long 26. 



24. Preanal sucker broken on each side, as well as posteriorly, by a papilla ; 



spicules equal, 400/i long ; eggs 63/t long by 35/t wide. 



Heterakis brevispiculum, p. 59. 



Preanal sucker not broken on each side, but only posteriorly, by a papilla ; 



spicules subequal, there being 50/i difference in their lengths ; the longer 



not over 370/* in length 25. 



25. Male 5.5 mm. long by 210/j. wide; preanal sucker 55/t in diameter; female 



6.6 mm. long by 300/i wide, its tail <ks of total body length ; eggs 50/t long 



by 30/t wide Heterakis beramporia, p. 56. 



Male 7.5 mm. long by 410/* wide ; preanal sucker 71/t in diameter ; female 

 7.6 mm. long by 460/i wide, its tail V s of total body length ; eggs 57/6 long 

 by 42/* wide Heterakis hamulus, p. 63. 



26. Spicules 110 and 130/t long respectively; tail of female 1/7.8 of total body 



length Heterakis macroura, p. 67. 



Spicules 260/* long or longer ; tail of female not as long as above except 

 possibly in H. dispar where length not given 27. 



27. Female 34 mm. long ; vulva in anterior part of body ; male 19 to 20 mm. 



long ; spicules not over 390/* long Heterakis brasiliana, p. 58. 



Female not over 23 mm. long ; vulva posterior to middle of body ; male 

 not over 18 mm. long; spicules 400 to 500/i long 28. 



28. Male 7.8 mm., female 11.6 mm. long ; eggs 70/* long. 



Heterakis caudata, p. 59. 



Male 11 mm. or longer ; female 14.8 mm. or longer ; eggs not more than 



62/* long 29. 



29. Male 11 to 18, female 16 to 23 mm. long; two lateral membranes present; 



vulva surrounded by a cuticular thickening ; in other hosts than below. 



Heterakis dispar, p. 62. 

 Male 13.1 mm. long, female 14.8 mm. long ; no lateral membranes and no 

 cuticular thickening of vulvar region described ; in Cygnus atratus. 



Heterakis circumvallata, p. 61. 



This key does not include Heterakis acuticaudata (p. 77), as the 

 evidence is at present inadequate for the allocation of that species 

 to this genus in its restricted sense. The key does not include the 

 four new species of Heterakis recently described by Chandler (see 

 Addenda, p. 385). 



HETERAKIS GALLINAE (Gmelin, 1790) Freeborn, 1923 



Synonyms. — Ascaris gallinae Gmelin, 1790; Ascaris vesieularis 

 Froelich, 1791, part; Heterakis vesieularis (Froelich, 1791) Dujar- 



