NO. 10 SCOTT: A NEW SPECIES OF NYCTERIBIIDAE 169 



setae on its lateral edges, and only two groups of about 3 or 4 short 

 setae at either angle of the hind margin, instead of an almost unbroken 

 series of 12 or more very long setae across this margin (the side margins 

 and hind margin of this tergite in B. pizonychus are slightly sinuate). 

 The divided second tergite is also much shorter, has rather numerous 

 short setae on the lateral parts of its surface, while the marginal setae 

 on either lobe are much more numerous, longer and stronger, hence the 

 2 or 3 very long ones at the inner angle of either lobe contrast less with 

 the rest of the marginal series than do the two very long setae near the 

 inner angle of either lobe in B. ferrisi. The third tergite consists of two 

 rather widely separated chitinous lobes, each having two long and sev- 

 eral short setae at the inner hind angle, and several other short setae 

 along the arcuate lateral margin. The anal prominence is the hindmost 

 part of the abdomen when seen from above. It has three setae of medium 

 length at either hind angle and several short setae on either lateral mar- 

 gin. The posterior part of the abdomen, therefore, also differs from 

 that of B. ferrisi, in which there is no counterpart to the divided third 

 tergite, and the anal prominence is posterodorsal in position. (In the 

 female specimen of B. pizonychus figured, and in several others, the 

 posterior dorsal part of the abdomen is occupied by a large dark patch 

 rounded in front, with several lighter spots, and extending into the 

 anal prominence; it is uncertain to what this condition is due, but it is 

 apparently not due to the presence of a larva seen through the trans- 

 lucent outer wall of the body.) Ventrally, the basal sternite in B. 

 pizonychus is short ; the whitish connexivum behind this has two trans- 

 verse rows of longer setae marking the hind margins of segments, the 

 surface of the anterior is covered with shorter setae, while the posterior 

 of the two has shorter setae in a single series near the hind margin in 

 the middle, and covering most of the surface at the sides. Behind this, 

 three segments, more or less chitinized, can be traced ; the front of these 

 three consists of a single series of longer setae, and has a very short 

 transverse chitinized strip at either side; the next is bluntly produced 

 in the middle behind, chitinized except for a narrow median strip, with 

 short setae on its surface and longer ones on the margin ; the hindmost 

 {i.e., the subgenital plate) has an arcuate hind margin, a chitinized 

 area on either side, with shorter and longer setae on the surface of the 

 chitinized parts, and along the margin. (In B. ferrisi the basal sternite is 

 long, and the remainder of the ventral surface almost entirely mem- 

 branous and less setose.) 



