Within the Order Chromadorida the ejaculatory duct has 

 very little musculature, and that is discernible only under 

 the most favorable conditions. From this standpoint, mem- 

 bers of the group are definitely closer to phasmidians such 

 as Rhahditis than are members of the other aphasmidian 

 group, the Enoplida. Diorchic* forms are the rule but 

 Enchromadora, Chromadora Monoposthia, Spirina, Epsil- 

 onema, Tripyloides, Desmoscolex and Greeffiela are all 

 monorchic. According to Cobb, some species of Monhystera 



"Monorrhic (with one testis) and liionhic (with two testes) 

 are here introduced as adjectives comparable to monodelphic and 

 didelphic which are used to denote the number of ovaries. 



and Cyatholaimus are monorchic. Examples of forms 

 known to be diorchic include Anaplechis granulosus, 

 Aphanolaimus spp., Bastkinia exiUs, axonolaimids, come- 

 somatids, cyatholaimids, Spilophorella paradoxa, Desmo- 

 laiimiH zeelandicus, Theristus setosus and Draconevia 

 cephalatum. Flexure of the gonoduct is limited to some 

 forms with one testis {Anaplectus granulosus sometimes 

 exceptional). 



The typical testicular arrangement (Fig. 124 O) con- 

 sists of two testes extending in opposite directions but 

 joined by a pair of seminal vesicles which may or may 

 not be clearly separated from one another by a tonstric- 



A-C — Rhabilitis terricola. (A — Cross section at level of seminal 

 vesicle : B — Vas deferens with ejaculatory glands on each side : 

 C — Testis just anterior to seminal vesicle). DP — Rhahditis lamb- 

 dieusis (D — At level of testis; E — Seminal vesicle; F — Vas def- 

 erens). G — Rhigonvma infectum (male gonoduct). H-K & S-T — 

 Metoncholaimus pristiurus (H — Blind end of testis; I — Growth zone 

 of testis ; J — Ejaculatory duct just preanal ; K — 

 Vas deferens ; S-^Ejaculatory duct mid-region ; T — Vas deferens 

 opposite seminal vesicle). L-Q — Enoplus communis (L — Ejacu- 

 latory duct just preanal ; M — Ejaculatory duct mid- 



region ; N — Vas deferens ; O — Ejaculatory duct ; P — Glandular 

 region vas deferens; Q — Sperm). R — Chromadora quadrilinea 

 (Junction of glandular and non-glandular regions of vas deferens). 

 U-Z — Heteroilera marioni (U-Y — Diorchic specimen; Sections at 

 intervals from anterior, posteriad in the order Y, U, V, W. X. 

 [X — Seminal vesicle]; Z — Specimen monorchic). AA-EE — Trilobus 

 t/racilis (AA — Showing vas deferens and seminal vesicle; BB — 

 Vas deferens and testis ; CC — Mid-region of ejaculatory duct ; 

 BE — Longitudinal section of ejaculatory duct). Original. 



154 



