Cobb — Nematodes, mostly Australian and Fijian. 17 



supplementary male organs are known in the genus except papillsB of another 

 character near the anus. 



There is an interesting dorsal organ on the head, — of unknown significance. It 

 -wall be noticed in the description of the species in which it has been observed. 



Key. 



Pharynx with one or two large teeth. 



Tail end (female at least) encircled by a few conspicuous rings 1. viviparus. 



Tail end not so encircled. 



Length of the female not exceeding 1-inm. 



Body slender (little more than 2-6 %); neck long (23- %) 2. parvus. 



Body not so slender (3 % and over) ; neck shorter (13- % to 22- %). 

 Female sexual organs asymmetrical (single). 



(Esophagus 16 % 3. monhysteroides. 



(Esophagus 20 % 4. minor. 



Female sexual organs double and symmetrical. 



Reflexed ovaries crossing each other 5. filicavAatus. 



Keflexed ovaries not crossing. 



(Esophagus swollen just behind the pharynx 6. australis. 



(Esophagus not so swollen. 



Body "4 mm. long 7. minima. 



Body '75 mm. long 8. graminum.* 



Length of the female 1 '5 mm. or more. 



Throat or pharynx with two equally well developed teeth 9. fluviatilis. 



Throat or pharynx with only one well developed tooth. 



Tail about half as long as the worm 10. trichuris. 



Tail about one-third as long as the worm 11. striatus. 



Tail about one-seventh (15 %) as long as the worm. 



Length 1-5 mm 12. macrodon. 



Length 2- to 2-5 mm 13. rivalis. 



Pharynx with only much less well developed teeth at the base. 



Female sexual organs single, asymmetrical 14. gracilis. 



Female sexual organs double, symmetrical. 



Throat or pharynx shallow (half as deep as wide). 



Lips distinct ; pharynx not striated 15. inermis. 



Lips indistinct ; pharynx striated 16. similis. 



Throat or pharynx as deep as wide, with small teeth at the base. 

 Length exceeding l-mm. 



Tail nearly one-third (30 %) as long as the worm 17. longioauda. 



Tail only one-fifth (16 to 20 %) as long as the worm. 



Width 4-% 18. yaiformis. 



Width exceeding 7 % 19. albm. 



* The unknown female of graminum is assumed to have double and symmetrical sexual organs not crossing. 

 C 



