NEMATODA. 



283 



Farn. 1 . Ascaridae. Body tolerably stout. Mouth with three lips furnished 

 with papillae, one of which is dorsal, while the other two meet- together in the 

 ventral line. Buccal cavity rarely furnished with pieces of chitin. Posterior 

 portion of oesophagus often forming a distinct pharyngeal bulb. Posterior 

 end of male ventrally curved, and usually furnished with two horny spicula. 

 Parasitic in the alimentary canal of animals. 



FIG. 231. a, male SpJiaerularia in its larval skin (Lc) x about 75. 6, female with partially 

 protruded vagina S. c, the same with still more developed uterine outgrowth S. d, uterine 

 outgrowth fully formed, containing ovary, oviduct, and uterus x 10 ; W the relatively minute 

 body of the worm. 



Ascaris L. Polymyarian, edges of lips dentated in the larger species. 

 Pharyngeal bulb not distinct ; hind end usually short and conical, and in the 

 male always provided with two spicula (Fig. 232) ; in Vertebrata. A. lumbricoides, 



