xii INTRODUCTION 



Genital cone. — A terminal or subterminal, postanal, ventral 

 process in male Strongyloidea, which may have on its ventral 

 surface a granular and thickened cuticle, referred to by some 

 authors as a dermal collar. 



Head. — Although there is no real head in Nematodes, the 

 anterior portion of the animal, carrying the mouth, lips and 

 cephalic papillae or other specialized sensory organs, is 

 frequently referred to as the " head." When this region is 

 marked off from the portion of the body following it by a 

 constriction, or by being itself of greater diameter, it is 

 described as distinct. 



Lateral organs. — Paired lateral subcuticular organs near the 

 anterior end of the body, presumably sensory in function, 

 occurring in many free-living forms and apparently homo- 

 logous with the lateral cephalic papillae of more highly- 

 speciaUzed parasitic forms. (The " amphids " of Cobb). 



Lips. — Clearly-differentiated structures surrounding the 

 mouth and bearing sensory papillae on their external 

 surfaces. 



Mouth-collar.— A ring-like cuticular sweUing sometimes 

 surrounding the anterior extremity, immediately behind 

 the mouth-opening, in the Strongyloidea. 



Ocelli. — Masses of pigment within the body-cavity, usually 

 closely connected with the oesophagus, and sometimes pro- 

 vided with hyaline lenses. (Referred to by some authors as 

 eyes or eye-spots). 



Oesophageal funyiel. — A funnel-shaped expansion of the 

 lumen of the oesophagus at its anterior end, immediately 

 behind its junction with the buccal capsule or pharynx. The 

 funnel is frequently lined with thickened cuticle. 



Ovejectors. — Specialized muscular portions of the female 

 genital tubes, near their junction with the vagina, serving to 

 control the deposition of ova. 



Oviparous. — Producing eggs which hatch some time after 

 deposition. 



Ovoviviparous . — Producing eggs which may or may not 

 have shells, and which hatch immediately after deposition. 



Pharynx. — Resembles a buccal capsule, but has an external 

 muscular coat. 



Sucker. — A depression supplied with muscles and with a 

 thickened cuticular border. In the absence of a thickened 

 cuticular border, such structures are usually referred to as 

 sucker-like organs. 



Supplementary organs. — Modified preanal or postanal 

 papillae on the ventral surface of the male in many free-living 

 genera, having frequently a more or less complex chitinoid 

 framework. (The " sucker-tubes " of Bastian, and the 

 " Haftorgane " of some German authors). 



