TWO NEW SPKOIES OF OMYCHOPHOKA. 511 



Fuitlier along the vasa deferentia, howevei-, the wall becomes 

 thinner, the muscular coat less developed, and the lining 

 cells less columnar. This feature becomes more and more 

 emphasised towards the point of uuion of the two genital 

 ducts, as can be seen on comparing figs. 40, 41, and 42. 

 At the above-mentioned point, however, there is a sudden 

 change in the characters of the lining cells as well as in the 

 muscular coat. In both the ascending and descending limbs 

 of the common duct the lining cells become columnar and, as 

 a rule, the cell limits are well marked. The muscular coat of 

 the ascending limb, howevei-, remains comparatively thin, 

 and even in the descending limb it only becomes greatly 

 thickened at the level of the antepenultimate pair of legs. 

 From that position onwards it is extremely thick, and the 

 term ductus ejaculatorius should be confined to this thickened 

 poition of the common duct (figs. 46, 47, and 48). 



The most interesting character of the male genital organs 

 of Eoperipatus is the great length of the unpaired duct, 

 which almost equals in extent that of the genus Peripatus. 

 The variation that occurs in the length of the unpaired 

 portion of the male organs in the Peripatida3 is a very 

 interesting feature. It is longest in the genera Peripatus 

 and Eoperipatus (7). In the genus Peripatoides it is not 

 so long (16), and is still shorter in Peripatopsis (2); but is 

 shortest of all in Paraperipatus, in which, according to 

 Willey, the unpaired portion of the male duct is hardly any 

 longer than tlie vagina [IS). Whether this feature of Para- 

 peripatus is primitive nuiy well be doubted, when the fact 

 that there are no spermatophores in this genus is taken 

 into consideration. As in the genera Peripatus and Peri- 

 patoides, there is in the unpaired duct of Eoperipatus an 

 enormously long spermatophore, which, however, lacks the 

 hornycoatdescribed by MissSheldon in P. Novae-Zealandite 

 (16), and by Gaff ron in P. Ed wards ii (7). It is nevertheless 

 provided with a horny cap, which covers its foremost end, 

 and this seems to be the only advance which it has made, in 

 the direction of forming a coat, from the condition described 



