NEMATODA 203 



Male is 8 to 9 mm., female 11 to 15 mm. long. Mouth sur- 

 rounded by three distinct lips. The body is gradually attenu- 

 ated toward the posterior part, and has two unequal spicules. 

 This parasite is found exclusively in the caeca and occasion- 

 ally in large numbers. Ova are elongated, capsule with full 

 granular center. 



(b) Heterakis differens.— This species is slightly larger than 

 the Heterakis papillosa attaining a length of 15 to 20 mm. 

 The mouth has no apparent lips. Has two spicules of equal 

 length and the posterior extremity of the female terminates 

 in a sharp point. It is usually found in the posterior part of 

 the intestine of chickens. Ova similar to H. papillosa. 



(c) Heterakis inflexa (Heterakis perspicilhim).— This is not 

 very common, and when present is found in the small intes- 

 tines. In length and appearance it is similar to the H. 

 differens. The host is the ordinary fowl. 



(d) Heterakis compressa is similar to above; occasionally 

 found in the small intestines of chickens. 



(e) Heterakis muculdsa.— This is the common parasite of 

 pigeons and often occurs in such large numbers as to prevent 

 their being reared, 400 to 500 are sometimes found in an 

 individual. The body is white and attenuated at both ends. 

 Male is 20-25 mm.; female 20-25 mm. long. 



(/) Heterakis crassa.— This parasite is common in the 

 duck. The male is 12 to 15 mm. long and the female 40 to 

 50 mm. Tail is thin, conical, and straight. 



(g) Heterakis lineata. —Heterakis lineata is rare; found in 

 the intestine of the domesticated duck. Its length is from 6 

 to 10 cm. 



(h) Heterakis dis par.— This species found in small intes- 

 tine of geese is closely related and similar to the H. papillosa. 

 Mouth has three very small lobes. Two lateral wings on the 

 neck becoming narrower toward the tail. Male 12 to 18 mm., 

 female 16 to 23 mm. long. This parasite is not very common. 



Pathology.— Young animals which have died from the dis- 

 order caused by the ascarides, show on autopsy large numbers 

 of this parasite which almost occlude the lumen of the bowel. 

 The stomach may also contain many of them. They are 

 found scattered along the intestines or coiled up in masses. 



