CXCVl 



FAUNA HAWAIIENSIS 



obvious. Reduviolus oscillans is typical of the first of these groups, and R. lusciosus 

 of the second, the latter with its allies forming the sub-genus Nesotyphlias of Kirkaldy. 

 R. oscillans and its near allies are all macropterous and exhibit little or no individual 

 variation in the development of wings and tegmina and the ocelli are perfectly formed. 

 In Nesotyphlias on the other hand the wings are reduced to extremely minute lobes, 

 the tegmina are hard and leathery, with the membrane always reduced, and the various 

 forms exhibit very great specific differences in the amount to which the tegmina are 

 shortened. The wings do not, so far as I have been able to examine the species, vary 

 in size in accordance with the difference in the size of the tegmina. Thus Nesotyphlias 

 lusciosus with its tegmina forming a perfect abdominal covering, and with much larger 

 membrane, has the same small, almost microscopic wings, as such a species as N. curti- 

 pennis, the tegmina of which fall far short of the apex of the abdomen. 



There is, however, one species of Hawaiian Rediiviolus, and that one of the 

 ' commonest and most widely distributed of all, which differs from all the others, in 

 having brachypterous and macropterous forms, as well as somewhat intermediate 

 conditions. It was described, no doubt from macropterous examples, by White, as 

 R. blackbiirni, there being no brachypterous specimens in Blackburn's collection. 

 Blackburn's specimens were such as are usually found in drier localities or at lower 

 elevations ; truly brachypterous forms inhabit wetter localities or higher elevations in 

 the mountains. I have taken some pains to observe this species at high elevations 

 above 4000 ft. in the mountains, where I have seen it breeding in numbers amongst 

 low sedges. In the most brachypterous form the membrane is much reduced in the 

 female, the tegmina not quite covering the abdomen, while the wings are much shorter, 

 though extending" somewhat beyond the middle of the abdomen. It will be seen, 

 therefore, that although the tegmina have suffered a reduction fully as great as in 

 typical Nesotyphlias lusciosus, the condition of the wings is entirely dissimilar, nor have 

 the ocelli suffered any apparent degradation. There is therefore a very great gap 

 between Nesotyphlias and the forms of R. blackburni, which form as it were a faint lead 

 to the condition of this always flightless sub-genus. In one other respect, in which 

 Nesotyphlias differs greatly from the fully- winged Hawaiian Reduvioli, R. blackburni 

 does make an approach to the former. Most of the winged forms have the pronotum 

 much widened posteriorly and this widened part, when seen in profile, is considerably 

 raised above the anterior portion. In Nesotyphlias this condition is exactly reversed, 

 the front part of the pronotum being convex and raised above the posterior part. 

 R. blackburni in its macropterous form is one of the few Hawaiian species, in which 

 the hind part of the pronotum is but little raised posteriorly, the profile of anterior and 

 posterior parts being about on the same level. In the brachypterous specimens the 

 condition of the pronotum is variable, but in many of these it is distinctly convex 

 anteriorly, and posteriorly is sunk to a lower level, in the same manner as in Neso- 

 typhlias. It should be noted that the external copulatory organs oi R. blackburni are 



