410 



Mr. H. A. Bay lis on a 



situated near the posterior end of the oesophagus, and has 

 vesicular structures in front of and behind it. 



In both sexes the tail is tapering and ends in a fine point. 



The caudal end of the male has no alse. There is a series 

 of oblique muscle-bands on either side, extending forward for 

 some 2 - 5 mm. in front of the cloaca, and in front of this a 

 row of sucker-like organs on the ventral surface, at regular 

 intervals, with radiating muscle-bands. These organs are 

 fusiform, with the long axis running antero-posteriorly ; they 



Fig-. 2. 



D.L. 



C.R. 



O-l mm. 



Falcaustra siamensis. The head, seen from its anterior aspect. 



D.L., dorsal lip ; N.P. 2., inner branch of pulp of papilla. Other 

 lettering as in fig. 1. 



are not provided with any chitinoid supporting structure, and 

 are similar to the single preanal sucker of Subulura and 

 certain other forms. Of three male examples available, two 

 possessed four of these organs, the third only three. There 

 are ten pairs of rather large caudal papilla? (figs. 3, 4, 5, 1-7, 

 9-11) and one median double papilla (figs. 3-5, §) just in 

 front of the cloacal aperture. Two pairs of postanal papilla? 

 (numbered 3 and 4 in the figures) are laterally situated, the 



