COBB: A KEY TO THE GENERA OF FREE-LIVING NEMAS 481 



Pharynx open, wide, icapacious 



Amphid round ; anterior pharyng. chamber large, posterior small ; setae 10 Bathylaimus Cobb 1894 



( = Macrolaimus Ditlev. 1918 

 = Cothonolaimus Ditlev. 1919) 



Amphid small, with internal pocket (Pandolaimus ?); pharynx of 1 chamber 

 Depth pharynx iequalling width; dorsal onch. small, ant., appressed Anoncholaimus Cobb 1920 

 Depth pharynx nearly twice width 



Wall of pharynx irregularly thick; amphid apparently circular Pandolaimvs Allgen 1929 



Wall of pharynx thin; amphid small, transverse-oval, with pocket Pelagonema Cobb 1894 



(cf. Vasculonema Kreis 1928) 



Pharynx narrow, often tubular or with closed lumen 

 The amphid behind level of cephalic setae 



Cephalic setae 0; pharynx $ head-width, with 3 refractive elements. . . Angustinema Cobb 1933 

 Cephalic setae present 



Nema over 3 mm. long Cynwa Cobb 1920 



Nema 0.6 mm. long Aplectus Cobb 1914 



The amphid in front of level of cephalic setae; cephalic setae 4 



Dorsal pharyng. wall not thicker; ampbidial glands large, conspic.; eyes 2 . . .lonema Cobb 1920 

 Dorsal pharyng. wall thick, tooth-like; amph. monospire at lips ; re net te far back 

 Oesoph. glands obscuring junct. of intest. ; dorsal phar. element uniform. . .Onchium Cobb 1920 

 Oesoph. glands not prominent; dorsal pharyng. element not uniformly thick, but heavy 



Tooth-like thickening parallel to axis Camacolaimus de Man 1889 



(^Digitonchus Cobb 1920 

 = Acontiolaimus Fil. 1918) 

 Tooth-like thickening bent outward from beginning of vestibule 



Point of "onchium" single Acmaeolaimus Fil. 1918 



Point of Y-shaped "onchium" duplex Ypsilon Cobb 1920 



