252 H. L. SHANTZ. 



The second antennae, or claspers, of the males differ rather 

 markedly in these three species. B. paludosa is distinct because 

 of the toothed inner margin of the first division, and of the grad- 

 ually tapering second division which ends in a bluntly rounded 

 point. In both B. coloradensis and B. Lindahli the distal ends of 

 the second antennae are turned in rather abruptly (PI. X., 7, 8 ; 

 PI. XL, 23, 24). B. Lindahli has, as a rule, shorter claspers than 

 B. coloradensis. But this cannot always be depended upon, for 

 the measurements show that it is not an uncommon thing to find 

 B. Lindahli with second antennae longer than those of B. colora- 

 densis, even though the body length of the latter exceeds by 

 several millimeters that of the former. There is, however, a con- 

 siderable difference in the average length of the claspers of these 

 two species. The average measurement of 40 specimens of B. 

 coloradensis is 5.33 mm., varying from 3.5 mm. to 9 mm. ; while 

 the average of 10 specimens of B. Lindahli is 3.87 mm., varying 

 from 2.26 mm. to 5 mm. ; the ratio between the averages of B. 

 coloradensis and of B. Lindahli is 1.37 to I. Only one individual 

 of B. coloradensis had claspers 9 mm. long, and this is -probably 

 exceptional, since the next longest measured only 7.2 mm. 



The basal division of the claspers of B. Lindahli is of about 

 the same thickness as that of B. coloradensis. It is somewhat 

 shorter, however, the ratio being I. to 1.49. The outer margin 

 of the first division of the clasper of B. Lindahli has a number of 

 very delicate sensory hairs. Near the base on the inner side 

 there is a raised portion bearing teeth (PI. X., 7 to). Teeth are 

 totally lacking as we approach the distal end. This division of 

 the claspers of B. coloradensis is notably different. The toothed 

 area is about half way between the ends on the inner side (PI. X., 

 8/cz). Near the base there is a prominent tubercle of considera- 

 ble length. This tubercle is characteristic of full grown males. 

 It is not plainly seen unless the clasper is bent forward, when it 

 stands out prominently on the inner side. It is often a third as 

 long as the width of the basal division (PI. X., 8/; PI. XL, 23). 



The second division of the clasper is about the same thickness 

 in the two species. The length is somewhat less in B. Lindahli 

 than in B. coloradensis. In each species the inturned portion 

 varies greatly in outline, depending on the point of view (PI. X., 7, 



