£y G ten . B : 1 



KEY TO THE MOST COMMON NBIATODSS OF AGKICULTURAL SOILS AND PLANTS 



Oesophagus rhabditoid (with valve in basal bulb as in PI. Ill, h) , 

 diplogasteroid (without valve in basal bulb as in PI. Ill, 5), 

 tylenchoid (PI. Ill, 6, 7, 8), or aphelenchoid (PI. Ill, 9). If 

 tylenchoid or aphelenchoid, always with stylet. Males of sorae 

 genera have a distinct bursa (PI. I, Fig, 2). Never with setae 

 or conspicuous amphids. Phasmids always present, but most often 

 difficult to locate. Mature females of some genera have a much 

 enlarged body, Phasmidia 2 . 



Oesophagus bulboid (PI. Ill, 3), cylindrical (PI. Ill, 1) or 

 dorylaimoid (PI. Ill, 2). Amphids often conspicuous, appearing 

 as circles, spirals, stirrup forms, etc. (PI. II, A, B, C, D). 

 Often with setae. Males without bursa. Always with elongate, 

 vermiform body. Aphasmidia 6. 



2. Stylet always present, usually, though not always, with well-devel- 

 oped, rounded knobs. Shapes and proportions of stylets vary 

 greatly with genera and species, but are usually recognizable as 

 variations of the form shown in PI. II, Fig. 3- Attached to the 

 stylet is a thin oesophageal tube which may be straight or coiled, 

 Tylenchida 3- 



Stylet absent. Anterior portion of oesophagus muscular (striated) 

 (PI. Ill, h, 5). Rhabditida U. 



3. Dorsal oesophageal gland orifice near base of stylet, or at most, 

 not more than one stylet length posterior to stylet knobs. The 

 oesophageal tube often has an abrupt bend at this point (PI. II, 

 Fig- 3). Stylet mostly with well-developed knobs. If stylet 

 knobs are absent, tail is lonp, and thin, Tylenchoidea 



Dorsal oesophageal gland orifice in median bulb and difficult to 

 locate. Oesophageal tube witliout abrupt bends. Stylet knobs 

 small or absent. Median oesophageal bulb occupying nearly full 

 width of body (PI. Ill, 9). Tail rounded or conical. 



Aphelenchoidea 



h. Oesophagus rhabditoid, with valve in basal bulb (PI. Ill, U) 5. 



Oesophagus diplogasteroid, without valve in basal bulb (PI. Ill, 

 5) Diplomas toridae 



5. Stoma cylindrical, usually much longer than wide (Plato II, 2), 



