BY J. J. FLETCHER, M.A., B.SC. 



557 



1-5 mm. apart while the male pores are about 4 mm. apart. The 

 three pairs of spermathecal pores are peculiarly placed. There is 

 a paii- of spermathecae in each of segments vn, vm and ix : these 

 Open posteriorly on segments ix, X and xi respectively ; that is to 

 say, each spermatheca opens on the second segment after the one 

 in which it is placed. The pores are slit-like, not inter-segmental 

 but situated well within the anterior margins, or even just in front 

 of the middle of their respective segments, and in a line with the 

 intervals between the second and third rows of seise. Nephridio- 

 pores not recognisable. 



The mesenteries from segment xv forward are thicker than 

 those which follow, but relatively are nothing like so thick as in 

 the other worms. 



The alimentary canal presents a muscular pharynx occupying 

 about segments n to iv, a short oesophagus in segment v, which is 

 followed by two globular gizzards, one in each of segments VI 

 and vii ; a narrow portion follows of which that in segments 

 vm and ix is thin- walled, but in segments x to xvi its walls 

 become thick- walled, glandular, and vascular. The part in 

 segment x is swollen and globular, less marked in xi to xin, but 

 there are no diverticula ; in xiv there is'a long piece thrown into a 

 half-coil to the right so that the dorsal vessel crosses it trans- 

 versely, a half coil to the left in xv, and another to the right in 

 xvi. In xvii the walls are thinner, and the calibre of the canal 

 suddenly increases, but for two- thirds of its course the noticeable 

 breadth arises not from its being a broad sacculated canal, but 

 because the thin-walled intestine, which is really of less diameter 

 than at first sight appears, is coiled like a corkscrew, there being 

 in contracted worms a half coil in each segment right and left 

 alternately. For the remaining third it is straight and forms a 

 rectum, which gradually decreases in breadth. 



The male generative organs comprise two pairs of testes 

 in segments ix and xn ; two vasa deferentia which branch in 

 segment xn and the anterior ciliated portions of which lie free in 

 segments x and xi ; and a pair of small prostates in segment 



