607 
laterally (c) and ventro-medially, and becomes narrower from this place 
backwards. Here the lumen becomes tri-radiate in transverse section 
through the presence of one large dorso-median and two latero- 
ventral thickenings of the wall, the pharyngeal sectors (e), this being 
the case in the pharynx of all adult Nematodes. On the three parts 
SIE 
Sa GE 
dees ET) SL 
in ----- muse 
SSE ET PEEN 
ict. 
LE es a 
Figs SD: 
Fig. 3. Anterior extremity of a larva, viewed from ventral side. @, total 
length 4.6 mm., catch N°. 37. << 120: 
of the pharyngeal wall (e), protruding inwards, we can observe different 
teeth close behind the mouth-cavity (fig. 4). On the dorsal wall a 
double tooth is situated medially; both latero-ventral walls possess 
two small teeth: the one being situated more dorsally, the other 
more ventrally. The two teeth, situated most ventrally, touch in the 
median line. In the larva, represented in fig. 3, the six pharyngeal 
39 
