ANGUILLULID^E FROM TROPICAL ORCHIDS. 89 



The seventh papilla is situated exactly laterally, the eighth 

 on the dorsal side of the body, being, therefore, sub-dorsal. 

 Three of the six pairs of sub-ventral papillae are situated 

 before and three behind the anus. The first and second 

 of these sub-ventral papillae are placed close together, one 

 behind the other, near the posterior end of the bursa ; the 

 third is almost as far distant from the second as from the 

 anus ; the fourth, which lies immediately in front of the 

 anus, is slightly more distant from the third than the third 

 is from the second ; the fifth about as far distant from the 

 fourth as the latter is from the third ; but the sixth sub- 

 ventral papilla is placed considerably further forward, and 

 is not visible on the figures. The distance indeed between 

 the sixth papilla and the fifth measures 60 /*, that between 

 the fifth and the first 38 fi, so that the two distances are 

 nearly in the proportion of 3 : 2. The seventh pair of papillae 

 lie exactly laterally, opposite the fourth sub-ventral, a 

 little before the anus ; the last or eighth pair finally is 

 situated sub-dorsally, on the tail itself, nearly opposite 

 the second sub-ventral. Whereas, in most other species 

 of the genus Bhahditis, the bursa-papillce are all lateral ; 

 in Bhabd. oxycerca, on the contrary, most of them are 

 sub-ventral, being placed on the ventral surface of the 

 body. It is in consequence of this quite exceptional 

 distribution of the papillae that, in a ventral view of the 

 bursa, only two of them, viz., the seventh and the eighth, 

 appear to be situated in the lateral portions of the bursa, 

 and appear to reach its external margin. In the usual 

 lateral position of these worms, on the contrary (fig. 3 c), 

 the six sub-ventral papillae appear to reach the margin of 

 the bursa : in this position it becomes also conspicuous 

 that the bursa does not expand over the whole ventral 

 surface of the tail, but only over the sub-ventral or lateral 

 parts of it, so that the ventral surface appears concave. 



