PREFACE 



THE authors wi.sh to exjircss tlicir aiipreeiation to tho various 

 workers and institutions wliich supported the first part. Sucli 

 support, even in so limited a field, will assure eompletion of 

 the series. 



Tins ])art, covering- as it does, the digestive tract and associated 

 structures, includes most of the characters commonly used in identifica- 

 tion. In order to give as compivhensive a survey as possible numy of 

 the illustrations are semidiagianniiatic (those not shaded). In all cases 

 they are based on camera lucida sketches. The side view series of 

 diagrams may be assumed to have the dorsal side at the readers left 

 unless otherwise specified. 



The authors wish to express their appreciation to Doctor G. 

 Steiner, Doctor J. R, Christie and ]\[iss K. i\[. Buhrer, all of the Divi- 

 sion of Nematology. U. ,S. Bureau of Plant Industry, for theii- helpful 

 criticism. 



B. G. C. & M. B. C. 



