41 



narrower anil proportionately longer than in the others. The metathorax is 

 much more like the male than in the two other genera. The two halves of 

 the scutum are broad, similar in form to those of the male, but more widely 

 separated. The scutellum has the peculiar transversely oblong form of the 

 male, but more exaggerated, being shorter and wider. The Hanks are much 

 wideband the pieces shorter than in the two other genera; the principal 

 difference being that the trochantines of the meso- and meta-thorax are much 

 wider, more triangular. In this and other respects, the thorax of the female 

 Pkigalia is much more like the male thorax than in Hybemia and Aniso- 

 pt*ri/z, and this difference in structure is correlated with the larger wings. In 

 all these characters, the female Phigalia is intermediate between the normal 

 phalsenid females and the apterous species. 



A third step towards the normal female form is seen in the female Ope- 

 rhoptera boreata. On examination of a male and female received from Europe, 

 I find the following differences between the sexes: The head is as large, if 

 not larger, in the female as in the male: but the eyes are still somewhat 

 smaller and less rounded. The front of the female is much wider. The 

 palpi are as large and well developed as in the male, being much longer than 

 in the three previously-named genera, while the maxillae are as long as usual 

 in normal females, being rolled up between the palpi. The occiput is rather 

 long and large; the epicrauium large, very convex; clypeal region square, as 

 long as wide; orbits well marked; the clypeus narrows a little in front, the 

 edge being distinctly emarginate; the mandibles as large and setiferous as 

 usual. The wings are erpial in size; the hinder pair being as large as the 

 anterior pair. They are marked as described beyond in the specific descrip- 

 tion. In the fore wing, the discal cell is very large. There is a large sub- 

 costal cell situated near the apex, and the median venules are very short. 

 The submedian fold is very distinct, and the internal vein well marked. 



The thorax is about as large as in the male; the two halves of the pro- 

 scutum and tegulse much as in the male. The mesoscutum is nearly square. 

 The scutellum is large; being half as long as wide. The metascutum is very 

 widely divided, the two halves being nearly as large as in the male; while the 

 scutellum is of the usual shape, but very short and wide. The episterna and 

 epimera collectively are shorter in proportion to the coxa? and trochantines 

 collectively than in the three other genera. The coxae and trochantines ol 

 the metathorax are much longer and narrower than those of the mesothorax. 



We thus have successive stages of degradation from the nearly winged 



I) P H 



