VI 



PHYLUM NEMATHELMINTHES 



153 



and six backwards (Fig. 77). Of the latter two are of a 



considerable size, and 



ruri in the dorsal and 



ventral lines respectively 



(dfavln.). 



The reproductive or- 

 gans are formed on a 

 peculiar and very char- 

 acteristic pattern. The 

 testis (Fig. 78, ts.) is a 

 long coiled thread, oc- 

 cupying a considerable 

 portion of the body- 

 cavity. At its posterior 

 end it is continuous with 

 the vas deferens. The 

 vas deferens, in its turn, 

 becomes continuous with 

 a wide canal, the vesicula 

 seminalis (vs.sem.}, which 

 opens by a short, narrow, 

 muscular tube, the ductus 

 ejaculatoriuS) into the 

 rectum. Behind the rec- 

 tum, and opening into 

 its dorsal wall, are paired 

 muscular sacs (s.) con- 

 taining the penial seta 

 (pn.s.) already noticed. 

 The anterior end of the 

 testis consists of a solid 

 mass of sex-cells ; pass- 

 ing backwards there is found a cord or rachis occupying 



