The Anatomy of OpisthoiJatiis cinctipes. 91 



accessory glands correspond best with the anal glands of Fcripatus 

 in the posterior position of their external openings, and both glands 

 are generally considered homologous and therefore nephridial in 

 origin [cf. figs. 1 and 2). 



In Opistlioixitus the posterior accessory glands being farther 

 forward (cf. fig. 3 with figs. 1 and 2) would appear to correspond 

 better with the anterior pair of postgenital nephridia in Peripatus, 

 especially as their complicated form (the division into three parts 

 and the vesicular carrot-shape of the basal part, from which the 

 efferent duct leads to the exterior) gives these glands in Opistliopatus 

 a striking resemblance to a nephridium, as depicted by Gaffron 

 (1883, fig. 28) or Balfour (1883, fig. 28). The similarity in the mode 

 of opening in the two pairs of glands in Opistliopatus cannot be used 

 as an argument in favour of their similar origin, since nephridia may 

 also discharge at the apex of a papilla (for instance, in the 4th and 

 5th pairs of legs). 



10. The external sexual openings. 



Male. — The ductus ejaculatorius opens externally by means of a 

 cruciform orifice with four subequal arms, corresponding to the arms 

 of the lumen and situated between four small spinous pads, which 

 are generally closely approximated to each other in the live animal 

 and in spirit specimens (fig. 1 S^), but are pushed widely apart by 

 the evagination of a portion of the ductus in the drowned specimen 

 drawn in fig. 11. These four pads are very characteristic of the 

 male, as they are not found in the female, and they form a good 

 character for distinguishing the sexes in this species. They closely 

 resemble the spinous pads of the legs in structure, and have the 

 form of four non-retractile and easily distinguishable tubercles^ 

 bearing on their surface a number of spines and numerous scales,. 

 but no primary papillae. 



Female. — In the female the cruciform nature of the sexual orifice 

 (fig. 7 ? ) is much less evident, owing to the reduction of the longi- 

 tudinal (median) slit, which being inconspicuous and generally not 

 readily distinguishable, except in sections, quite escaped my notice 

 when the type specimens were first examined and described. The 

 transverse slit, on the other hand, is very large and conspicuous, 

 much larger, in fact, than in the male. The lips of the orifice, as 

 stated above, differ from those of the male in having no spinous 

 pads, but there are a number of ordinary papillae in the immediate 

 neighbourhood, each bearing the usual single spine. In the live 



