NEMATODE PARASITES OF BIRDS 



61 



to cloacal aperture and 1 at side of sucker). Cloacal aperture promi- 

 nent, the sucker, which is also prominent, 194/a anterior to it. Johns- 

 ton's description of the spicules is confusing. He states : " The 

 spicules are 1.17 mm. in length and 0.013 mm. in breadth. The 

 longer male spicule is strongly curved, and has a fairly uniform 

 breadth (0.008 mm.), but tapers slightly toward the extremity. 

 The length is 0.48 mm. The shorter spicule has a length of 0.18 

 mm., and a breadth (in its mid-region) of 0.012 mm., but the ex- 

 tremity is widened and rounded." The spicule which Johnston 

 figures agrees with the first length given, being about 1.1 mm. long. 



Female 7.7 mm. long by 260/* wide. Vulva just posterior to middle 

 of body (4.2 mm. from anterior end). Anus 530/* from posterior 

 end. Eggs in uterus embryonated. 



Life history. — Probably similar to that of H. gallinae (p. 54). 



Distribution . — Australi a ( Sydney ) . 



Figs. 70-82. — 79, Heterakis caudata. Male tail. After Linstow, 1906. 80, 

 Hetekakis chenonettak. Male tail. After Johnston, 1!>12. 81, Hetera- 

 kis OIRCUMVALLATA. MALE TAIL. AFTER LlXSTOW, 190G. 82, HETERAKIS 



dispar. Male tail. After Railliet, 1893 



HETERAKIS CIRCUMVALLATA Linstow, 1906 



Host. — Cygnus atratus, black swan, a species from Australia; not 

 Cygnus olor. Gedoelst lists this worm from G. olor, but it is doubt- 

 ful if it has ever been correctly reported from this host. 



Location. — Cecum. 



Morphology. — Heterakis (p. 50) : Head with 3 hemispherical lips. 

 Esophagus short, with terminal bulb : intestine at origin wider than 

 esophagus. 



