NEMATODA 



217 



Fig. 346 



Diplogaster rivalis 



(Siissw. F. Deut.). 



A, whole worm 



B, head. 



1. ANGUILLULA Ehrenberg. Cuticula smooth and ringed ; body elon- 

 gate, tapering behind; vulva behind the middle; spicules long; no 

 bursa: several species. 



A. aceti (0. F. Miiller). Vinegar eel. Length 2 

 mm.: in vinegar, living on the fungus forming the 

 " mother, " also in stale paste; has also been found in 

 the human bladder. 



2. DIPLOGASTER M. Schultze. Body elongate; 

 cuticula ringed and often ridged; body tapering be- 

 hind ; mouth with 2 or 3 teeth and often with papillae 

 around it; male with or without bursa: numerous 

 species; in fresh water, earth, and decaying sub- 

 stances. 



D. rivalis Leydig (Fig. 346). Length 2 mm.; 

 hind end tapering to a long, fine point; mouth sur- 

 rounded by a membrane around which are 6 short bristles: viviparous; 

 common in ponds and streams. 



3. RHABDITIS Dujardin. Minute worms living in decaying sub- 



stances or the ground; head end often constricted: 

 mouth triangular, usually with 3 to 6 lips; body 

 slender, ending with a point; male with 2 short 

 spicules: many species. 



R. terricola Duj. Body without distinct rings, 1.4 

 mm. long; mouth cavity long, with 2 ring-shaped thick- 

 enings at its base: common. 



4. HETERODERA Schmidt. Minute worms infecting 

 the roots of various plants, with a spine in the mouth 

 for piercing plant tissues: 1 species. 



H. schachti* Schmidt (H. radicola 0. F. Miiller) 

 (Fig. 347). Male 1.5 mm. long, .045 mm. thick; female 

 1 mm. long and viviparous, being .5 mm. thick when 

 full of young: in the roots of various vegetables and 

 other cultivated plants, causing swellings. 



5. SPHJERTJLARIA Dufour. Minute worms, free- 

 living and parasitic; male with a bursa; mouth with a 

 tooth: 1 species. 



S. bombi Duf. The young animals, about 1 mm. 

 long, live in the earth; after pairing, the fertilized 

 females migrate into the body of a hibernating queen bumblebee; here 

 the uterus, filled with growing larvae, evaginates out of the vulva and 



Fig. 347 

 Heterodera 



schachti 

 (Stone and 



Smith ) . 



1, pharynx ; 2, 

 intestine ; :i, ex- 

 cretory pore ; 4, 

 genital pore and 

 anus ; 5, testes. 



* See "Nematode Worms in the Greenhouse," by G. E. Stone and R. E. Smith, 

 Bull. No. r.5, Hatch Exp. Sta. of Mass., Ag. Col., 1898. 



