INTRODUCTION xi 



the generic name originally given to the genotype of each 

 genus, wherever this has subsequently been changed. 



Deftnttions 



In descriptions of Nematodes, the same term is not infre- 

 quently used by different authors to denote quite different 

 structures ; it is therefore necessary to define the more impor- 

 tant descriptive terms used in this work. 



Accessory piece. — A more or less strongly-chitinized struc- 

 ture (frequently serving as a guide for the copulatory spicules), 

 developed in connection -ndth the dorsal wall of the cloaca of 

 the male. (By many authors this structure is called the 

 gubernacidum). 



Buccal capsule. ~A cavity into which the mouth leads and 

 which opens behind into the oesophagus, and having a chitin- 

 oid wall which is not surrounded externally by muscular 

 tissue. In some famihes the duct of a dorsal oesophageal 

 gland is visible in the wall of the capsule, and is referred to as 

 the dorsal gutter. 



Buccal cavity. — This term is sometimes used where it is 

 difficult to determine whether the structure referred to is a 

 buccal capsule or a pharynx. 



Buccal valves.~The shell-shaped, chitinoid, lateral halves 

 of the buccal capsule wall, when it is not a continuous structure. 



Biirsa. — A cuticular expansion of the caudal end of the 

 male in the Strongyloidea, supported by a definite system of 

 " rays." (Cuticular expansions of the caudal end not supported 

 by this definite system of rays are referred to as caudal alae). 



The following nomenclature is adopted for the rays of the 

 bursa : — 



Ventral rays-f^'f ^'■°"''''"^'f ' 

 '' (. latere- ventral. 



j antero-lateral, 

 Lateral rays - medio-lateral, 



[postero-lateral. 

 Externo-dorsal rays. 

 Dorsal ray. 



Caudal glands.— \Jmce\Mav glands in the caudal region 

 commonly present in free-Hving forms, and producing a 

 cement-like secretion which may serve for fixation to solid 

 objects. For the speciaHzed terminal portion of the common 

 duct of these glands Cobb's term spinneret is emploved 

 (This corresponds to the " caudal sucker " of Bastian). 



CorcZon^.— Grooves, tubular channels or festoon-like orna- 

 ments in or on the cuticle of the cervical region. 



Dentigerons ridges.—Rows of denticles situated on the 

 inner surface of the lips. 



