SEXTTAL PHASE IX INDIAN NAIDID.l^.. 461 



vvlieu tlisteiided with the male products, may reach as far bade as 

 segment xii. The vns deferens, one on eacli side, is a. sliort tiihe 

 \vith only a single liend ; in diametei' it is 15 yu, except where it 

 joins the atrium, whei'e it is only 9 /u, ; it has a uniform lining 

 of culdcal epithelial cells. It passes vertically downwards from 

 the funnel on the posterior face of septum 5/6, and then after a 

 slight bend enters the atrium on its anterior aspect close to the 

 origin of the ejaculatory duct. 



The neck of the male funnel lies in the mouth of the sperm- 

 sac (seminal vesicle). The funnels fill up the mouth of the sac, 

 and are directed upwards and backwards just within it ; they 

 meet each other in the middle line above the gut by their inner 

 margins, and theii' outer surfaces are fused with the contiguous 

 part of the wall of the sac. They are cup-shaped, with everted 

 lips, and are lined by columnar ciliated cells with prominent oval 

 imclei at the base. The greatest diameter of the funnel is 

 about 45 /x. 



The atria are ovoid chambers with their long axes vertical, 

 l3'ing one on each side of the seminal vesicle in segment vi. Each 

 is 80-90 /A in height and 45-50 /x in breadth, and is lined by an 

 epithelium of cubical cells with indistinct outlines and coi:i- 

 spicuoiis nuclei ; outside the epithelium is a thin coat of circular 

 muscular fibi'es, outside which again the peritoneum is indicated 

 by a few scattered nuclei. The lumen may contain spermatozoa 

 or only a little coagulum. The ejaculatory duct is short, 

 about 30 fi ; its epithelium consists of closely packed columnar 

 cells with large peripherally situated nuclei ; it has a fairly thick 

 investment of circular muscular fibres. The duct may be in- 

 vaginated into the base of the atrial cavity ; it opens to the 

 exterior in the depth of a short tubular depression of the ventral 

 body-wall, about 15 /a in length, which is narrower at the surface, 

 and broader above, where it receives the duct. There are no 

 " prostatic" cells in connection with vas deferens or atrium. 



A thick band of muscle-fibres runs vertically Tipwards from the 

 ventral body-wall, lying internal to the atrium and supporting 

 the setal sac containing the penial sette. 



The ovisac, formed by the backward bulging of septum 6/7, 

 surrounds the sperm-sac which lies within it. It may reach back 

 to segment xvi. ; it contains a large mass of yolk granules, which 

 stain faintly with eosine ; and in its hinder part a number of 

 ova. The septa of the several segments behind the seventh 

 retain a transverse position between the body-wall and the ovi- 

 sac, fusing closely with the periphery of the latter. Large 

 blood-vessels are seen closely applied to the sperm-sac and inner 

 face of the ovisac. 



The female funnels are attached to the anterior face of septum 

 6/7 near the ventral parietes ; the cells lining it are small, and 

 appear to be modified peritoneal cells containing little else than 

 nuclei. In one specimen the funnels were seen to open on the 

 venti'al surface at about the level of septum 6/7. They are seen 



