NEMATODE PARASITES OF BIEDS 49 



KEY TO FAMILIES OP ASCAROIDEA 



Mouth with 3 lips or without lips. Males with a preanal sucker which may 

 be limited by a ring, or formed by a simple longitudinal depression. 



Heterakidae, p. 49. 



Mouth with 3 prominent lips, or with 3 main lips and 3 intermediate lips. Male 

 without preanal sucker Ascaridae, p. 135. 



Family HETERAKIDAE Railliet and Henry, 1914 



Synonym. — Heteracidae Railliet and Henry, 1914. 



Family diagnosis. — Ascaroidea (p. 48) : Polymyarian. Mouth pro- 

 vided with 3 lips or without lips and of variable shape. Esophagus 

 cylindrical or club-shaped, often followed by a distinct bulb. Males 

 with a preanal sucker which may be limited by a chitinous ring or a 

 delicate cuticular membrane, or formed by a simple longitudinal de- 

 pression. Two spicules, one or both of which may tend to atrophy 

 or show imperfect chitinization, and with gubernaculum present or 

 absent. Vulva usually near middle of body. 



Type- genus. — Heterakis Dujardin, 1845. 



The Heterakidae, including Heterakis, Ascaridia, and Suhulura, 

 are placed in the superfamily Ascaroidea in accordance with Railliet 

 (1916), Baylis (1923), etc. Travassos (1920) separated Heterakis 

 and Ascaridia, putting the former in the Oxyuroidea, the latter in 

 the Ascaroidea. The musculature, however, is identical in the two 

 genera and is polymyarian, whereas that of the Oxyuridae is mer- 

 omyarian; this similarity of the musculature of Heterakis and As- 

 caridia is accepted as the fundamental basis of classification by the 

 present author. Ascaridia has features very comparable with those 

 of Ascaris, the chief difference between the two being the sucker, the 

 presence of which in Ascaridia forms the transition between Ascaris 

 and Heterakis. The differences between Ascaridia and Heterakis 

 seem to merit only generic rank, not superfamily rank, as in Travas- 

 sos' classification. Seurat (1918) states that the genital tubes ©f 

 Ascaridia galli (=A. perspicillum) are identical with those of the 

 heterakids, showing the affinities of Ascaridia with Heterakis. 



KEY TO SUBFAMILIES OF HETERAKIDAE 



Mouth with 3 well-defined lips. Esophagus with 01' Without bulb; sucker of 

 male nearly circular and having a cutinous (chitinous) rim. 



Heterakinae, p. 49. 



Mouth with lips inconspicuous or wanting, followed by a vestibule; esophagus 

 with bulb; sucker of male spindle-shaped, without a cutinous (chitinous) 

 rim Subulurinae, p. 104. 



Subfamily Heterakinae Railliet and Henry, 1912 



Subfamily diagnosis. — Heterakidae (p. 49) : Mouth with 3 well- 

 defined lips; esophageal bulb present or absent. Preanal sucker 



