8 BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



HELIGMOSOMIDAE, new family 



Family diagnosis. — Trichostrongyloidea (p. 7) : Body frequently 

 coiled in a spiral, but not so rolled in some genera. The presence of 

 1 ovary is characteristic of this group among the trichostrongyles. 



Type genus. — Heligmosomum Eailliet and Henry, 1909. 



Subfamily Heligmosominae Travassos, 1914c 



Subfajiuily diagnosis. — Heligmosomidae (p. 8) : Characters of the 

 family. 



Type genus. — Heligmosomum Railliet and Henry, 1909. 



As this family and subfamily are not yet represented among 

 nematodes of birds they are not discussed further and the family 

 is erected here only in order to maintain uniformity of rank in 

 connection with other necessary changes. 



Family TRICHOSTRONGYLIDAE Leiper, 1912 



Family diagnosis. — Trichostrongyloidea (p. 7) : Buccal capsule 

 absent. Male with well-developed caudal bursa of typical form and 

 size, and with 2 equal spicules, sometimes accompanied by a gorgeret 

 or telamon. Eggs segmenting when deposited. Development direct 

 arid simple. Parasites of the digestive system. 



Type genus. — Trichostrongylus Looss, 1905. 



Subfamily Trichostrongylinae Leiper, 1908 



Subfamily diagnosis. — Trichostrongylidae (p. 8) : Characters of 

 the family. 



Type genus. — Trichostrongylus Looss, 1905. 



It will undoubtedly be necessary in the near future to break up 

 the new superfamily Trichostrongyloidea into a number of families 

 aiid to create new subfamilies, but in view of the meager representa- 

 tion of trichostrongyles among birds no consideration has been 

 given this matter in this paper other than proposing the family 

 Heligmosomidae. 



KEY TO GENERA OP TRICHOSTRONGILINAE 



1. Spicules typically trifurcated for two-thirds of their length; prebursal 

 papillae present; gubernaculum (or, more properly, telamon) typically 

 with lateral processes tending to form a ring partially encircling the cloaca 



as a spicule guide Ornithostrongylus, p. 11. 



Spicules not trifurcated, but with twisted appearance due to ridges and with 

 proximal end thickened at one side ; prebursal papillae rudimentary or 

 absent; wedge-shaped gubernaculum present Trichostrongylus, p. 9. 



