150 Mr, II. A. Baylis on Aspido Irllu^, 



prostomiiiin. There is a large plmrynx with very niuscuhu- 

 root", and hirge niuschs exteiuliiig from if, mainly buckwardfs, 

 to the body-wall. Beliiiid this there is a rather narrow 

 CEsophagus extending from the third to the fifth segment, 

 while the sixth segment contains a lobed and saccular diver- 

 ticulum of the oesophagus, lined with cilia, which is very 

 jrobably the homologue of the calciferous glands of earth- 

 worms. Behind this the intestine becomes large and 

 voluminou-J, and its contents appear to consist chiefly of 

 earth and vegetable debris, suggesting that the animal is not 

 in any sense a true parasite, but rather a commensal, of the 

 eaithworm " host," and that it avails itself of the latter as a 

 means of transport to favourable feeding-grounds. 'J'lie 

 digestive portion of the intestine is covered externally with 

 large flask-shaped cells, the expanded portion of wJiich 

 ])roj cts into tlie coelom. These, perhaps, represent the 

 chloragogen-cells of other oligochpetes. 



The intestine runs directly to the anus, becoming narrow 

 as it passes backwards. It shows a constriction at the point 

 where it jjerfoiates each septum, and a slight expauiion in 

 each segment. 



A pan- of nephridia have been seen in each segment from 

 the sixth to the ninth, and in some of the segments which 

 compose the caudal "shield," but neither the occurrence nor 

 the structure of the nephridia has been worked out in detail. 

 Large lobed sperm-sacs, containing clumps of sperm- 

 mother cells similar to those of earthworms, and sperm in 

 various stages of formation, are found arranged more or less 

 symmetrically in segments viii.-x., and in tiie tenth segment 

 they contain a pair of large ciliated funnels, connected, appa- 

 rently, by long and much convoluted ducts with the apertures 

 already mentioned at the sides of the ventral sucker. 



The ovaries are very peculiar, and need further study. 

 There appear to be on either side, in segments ix.-x., four 

 small rounded clumps of ovarian cells, as well as large 

 masses which appear to be ova with a very abundant supply 

 of yolk. These eggs are very large in proportion to the size 

 of the animal, and seem to be developed, one or two at a 

 time, from the ovarian clumps, which are apparently floating 

 freely in the coelom. How the ova escape when ready for 

 lajing is at present unknown, no trace of female ducts 

 having yet been lound. 



At the sides of the third segment there are a pair of 

 openings with thickened fleshy lips, which lead into what 

 appear to be the spermathecie. Tiicbe are a pair of tubes 



} 



