NO. 2131. 



NEMATODE PARASITES OF RODENTS— HALL. 



45 



Genus HETERAKIS Dujardin, 1845. 



Synonym,. — Heteracis Molin, 1858c; Ganguleterakls Lane, 1914, 

 Generic diagnosis. — Heterakinae (p. 44) : Mouth with three lips. 

 Esophagus subcylindrical, progressively swollen toward its posterior 

 extremity and with a distinct bulb. Two lateral membranes present 

 or absent. Males with caudal alae well developed to form a bursa 

 sustained by papillae of raylike appearance. Spicules generally un- 

 equal, at times equal or subequal, with- 

 out accessory piece. Preanal sucker 

 with a distinct chitinous ring. Females 

 with vulva toward the middle of the 

 body, the uterine branches passing in 

 opposite directions. The eggs have a 

 thick shell. 



Type-species. — Ileterakis vesicularis U 



(Froelich, 1791) Dujardin, 1845. 



HETERAKIS SPUMOSA Schneider, i866. 



Synonyms. — HeteraMs dahomensis 

 Gendre, 1911 ; Ganguleterahis gangula 

 Lane, 1914. 



Specific diagnosis. — HeteraMs (p. 45) : 

 Head 70 to 80 [jl in diameter. Mouth 

 with three distinct subequal lips; each 

 lip w ith two lateral papillae and appar- 

 ently one median. 



The small mouth cavity is followed 

 immediately by the esophagus. About 05 

 to 75 [X from the head end the esophagus 

 lumen dilates transversely and abruptly 

 narrows to its original diameter. Ex- 

 clusive of the bulb, the esophagus is 

 625 to 685 [JL long and 60 to 70 [/, in 

 diameter; the bulb is 250 to 300 \x 

 long and 125 to 170 [;. in diameter. 

 The cavity of the bulb is dilated posteriorly and lined with a chiti- 

 nous investment, the shape of the cavity varying with the contrac- 

 tion of the bulb. The lining of the esophagus proper shows a deli- 

 cate transverse marking. The cuticle shows a fine longitudinal and 

 transverse striation. A short distance back of the head a lateral 

 membrane (fig. 50) originates and rapidly attains its maximum de- 

 velopment, gradually diminishing posteriorly and continuing to the 

 posterior end of the body. The two cervical papillae are about 225 

 to 250 fi from the anterior end of the body. The excretory pore is 

 about 440 ^i from the head end. 



''/lomiTi:' 



Fig. 50.— HETERAKIS SPUMOSA. AN- 

 TERIOR EXTREMITY OF FEMALE. 



