NO. 6 CLASSIFICATION OF NEMATODES FILIPJEV 63 



Pl. 8, Fig. 67. Paratylenchns nanus Cobb, a representative of a highly spe- 

 cialized genus of the Tylenchidae; the triple spear is very 

 large, the preneural bulb is the only one that retains its 

 musculature, the cardiac bulb being composed of gland cells 

 only. After Cobb, 1925. 



Fig. 68. Iota octangulare Cobb, another highly specialized form of the 

 same family. Note the huge spear and the scalelike differ- 

 entiation of the cuticle. After Cobb, 1914. 



Fig. 69. Rhabdias sphaerocephala Goodey. Note the remnants of the 

 preneural bulb, characteristic of the Anguillulata ; in other 

 species of the genus there are no more hints of it in the 

 si'ngonic generation, but it is always very clear in the bi- 

 sexual one. After Goodey, 1924. 



Fig. 70. Cylichnostonmni auriculatiim Looss, showing the bursa of the 

 male, characteristic of the males of all the members of the 

 family Strongylidae to which it belongs ; it could be ex- 

 plained as a specialization of the bursa of some form of 

 Rhabditis (compare figs. 62 and 63). After Looss, 1901. 



