truded through the mouth opening. A few American species have, besides 

 the principal pharynx, multiple pharynges attached to the anterior por- 

 tions of the posterior intestinal rami, which project into the common 

 pharyngeal chamber (polypharyngeal species). 



The space between the epidermis with its underlying basement membrane 

 and the gastrodermis or intestinal epithelium is filled with a loose 

 parenchymatous tissue or mesenchyme in which the remaining organs are 

 embedded. The central nervous system if formed by a pair of cerebral 

 ganglia or brain in the head, from which a pair of ventral nerve cords 

 extend to almost the posterior end, connected by numerous transverse 

 commissures. From these parts originate many nerves running to various 

 organs and to a nerve plexus located below the epidermis. 



Fig. 3. Reproductive system. A, dorsal view (female gonads 

 indicated on left, male gonads on right side); B, generalized 

 diagram of the copulatory apparatus in sagittal section, 

 ac, common genital atrium; ad, adenodactyl; am, male atrium; 

 b, copulatory bursa; bd, bursal duct; br, brain or cerebral 

 ganglion; gp, gonopore; m, mouth; od, oviduct; ode, common 

 oviduct; ov, ovary; p, penis; pa, parenchyma; pb, penial 

 bulb; ph, pharynx; pp, penis papilla; sph, sphincter; sv, 

 spermiductal vesicle; t, testis; v, vagina; vd, vas deferens; 

 vs, seminal vesicle. 



