Syt;b':ri. A:2 



iit^w species are studied and better working methods are develooed, the 

 taxonomy must change. 



In this course, emphasis has been placed on the most common soil and 

 plant parasitic nematodes. Two keys for identification of these forms 

 are presented. The first of these, the "Ke.v to the Most Common liematodes 

 of Agricultural Soils and Plants," permits identification to f airily or 

 subfarailv. Once this identification has been made, identification to 

 genus can usually be made by reference to the illustration and descrip- 

 tions in tne appropriate section of Goodey more quickly than by ttie use 

 of additional keys. The second "Key to the J.ature Females of the Tylen- 

 choidea" was designed to facilitate identification to genus of the great- 

 er part of the plant parasites. Both keys have been siraolified by omis- 

 sion of rare forms. While this simplifies construction and use of the 

 keys, it also in>plies that rare forms vjill not "key out." 



In use of the keys, it should be kept in mind that keys are imperfect 

 tools at best and that verbal descriptions are very apt to be misleading. 

 Consequently, the use of the keys should be supolemented by frequent 

 reference to the illustrations in Goodey or other available publications. 

 Also, it is suggested that time and effort will be saved if no attempt is 

 made to identify larval forms (without sexual organs). VJhen possible, 

 several specimens should be studied. Visibility of the key characters 

 varies with specimens, and structures which are obscure on one may be 

 plainly visible on another. vJlien a tentative identification has been 

 made, available illustrations should be carefully checked. 



