SEGMENTAL ORGAN OF PODARKE OBSCURA. 



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the dissepiment. This fold is present only at the distal anterior 

 end of the ventral edge where it forms a short lip. 



Immature specimens show the ciliated organ lying directly on 

 the dissepiment, from the cells of the peritoneal covering of which 

 it develops. In mature forms the organ does not lie against the 

 dissepiment except at the point of union with the nephridium. In a 

 sagittal section (Fig. 2) the organ is raised from the dissepiment. 

 Although consisting of only one layer of cells, it may be folded 

 in such a way as to give the appearance of more than one layer. 

 This condition is seen in Fig. 2 ; if it were not compressed, it 

 would have the appearance of the organ- as seen in Fig. 3. 



bv 



Fig. 3. X 5°°- A sagittal section of the segmental organ showing an egg passing 

 along the ciliated surface. C. O, ciliated organ ; E, ovarian egg ; N, nephridial 

 sac ; B. V, blood vessel. 



The ventral lip is not shown in either of the sagittal sections 

 as they passed through the union of the nephridial tube and 

 ciliated organ, whereas the ventral lip which is short and found 

 only at the anterior edge (as has been stated), would appear in 

 earlier sections in the series. 



I have not found any indication of an internal termination of 

 the nephridium other than the ciliated organ, and it seems evident 

 that the latter forms an open ccelomic funnel. Its nature may 

 best be considered after an examination of its relation to the dis- 

 charge of the sex products. 



