PHYLUM NEMATHELMINTHES 



181 



extremity. The anus is located near the posterior tip of the body, 

 and in the male the reproductive aperture and two penial setae or 

 spicules are located just within this opening. 



Internal Anatomy 



The body wall is composed of the thin, outer, smooth cuticle, the 

 epidermis, whose cells run together, and a thick layer of longitudi- 

 nal muscle fibers, whose medial margins are rather baggy. There 



/?70uth circumesopfiagea/ 



aterc/s oyan'es ^ 



ov/c^ucts I \ pseudoooe/ 



excretort/ p/)ari/r}jc ^er7ti;a/ /x>re /r?i>€sC>/r?6 i)oc/i/ yya// 



Ct/7a5 



tiactas deferens 

 se/7?//7a/ ves/ch 



• e/acL'/atory afc/ct 



psei/cfocoe/ 



cut/c/e 1 intestine 



ep/c/er/T}/5\ body ivcr// 



^em/'na/ ves/c/e 

 seta/ soi 

 recta/r? 



pseadocoeJ 



musc/e ) 

 cutic/e 

 inteet/'ne 



ej(cretoru cana/ 



pe/ifcfl_ 

 o//dact setae: 



oyan/ 

 ner/e oord 



a/7i/: 



3 



'/Vi/sc/e 

 at/c/e 

 ep/der/nh 



Fig. 91. — Internal anatomy of Ascaris Iwmbricoides. A, Diagram of lateral view 

 of dissection of female ; B, cross-section of tlie midregion of the body of female ; 

 C, longitudinal section of posterior portion of male ; D, reproductive system of 

 female; E, reproductive system of male. (From Curtis and Guthrie, Textbook of 

 General Zoology, published by John Wiley and Sons, Inc., modified from Leuckart.) 



are thickenings of the epidermis in the positions of the longitudinal 

 lines. The excretory tubes follow the lateral lines. The body cavity 

 of this animal is a primitive or false coelom which is lined externally 

 by the mesoderm of the body wall and internally by the endoderm 



