2692 Insects. 



normal fore wings, — that the Coleopterous genus Atractocerus has the 

 fore wings nearly as small as those of Stylops, and, as in that insect, 

 situated at the extreme anterior margin of the mesothorax ; while in 

 the genera Cupes, Lymexylon and Hylecoetus, always united in a 

 family group with Atractocerus, the fore wings have a normal size, 

 figure and situation. Reviewing the other classes, we find that 

 in Diptera the fore wings are the sole organs of flight; in Lepidop- 

 tera and Hymenoptera they bear a chief part in the function of flight; 

 in the typical Neuroptera they share it equally with the hind wings ; 

 in Hemiptera they subserve the same purpose, although their struc- 

 ture — especially in the Cimicites — partakes rather of the protecting 

 character so marked in Coleoptera. Hence in this respect Stylops has 

 no affinity with any classes except Coleoptera and Orthoptera. The 

 mesothorax, as well as the fore wings, recedes to its minimum of de- 

 velopment in Orthoptera, Coleoptera and Stylops. The hind wings 

 and metathorax, on the contrary, have acquired an exclusiveness of 

 function and a maximum of development in Coleoptera and Orthop- 

 tera; and for these characters Stylops is still more remarkable, ex- 

 ceeding any insect or group of insects previously known in the 

 enormous development of its metathorax. A careful comparison of 

 this segment in Coleoptera, Orthoptera and Stylops, will disclose many 

 points of similarity, more especially as regards Coleoptera and Stylops, 

 — a point which I would willingly discuss at greater length, were it 

 not that the hind wings furnish still more conclusive evidence. To 

 these organs I would invite particular attention : their irregular mode 

 of folding and the paucity of their nervures, together with the entire 

 absence of transverse or reticulating nervures, show that there is no 

 affinity between the hind wings of Stylops and those of the Orthopte- 

 rous locusts, with which the enlarged metathorax had induced us to 

 compare them. But precisely as the hind wings of Stylops recede from 

 the numerously veined and fan-like organs which are so conspicuous 

 and ornamental in Orthoptera, so do they approach the sparingly veined, 

 amorphously folded, inconspicuous hind wings of Coleoptera, so that 

 at this point the line of affinity — previously running parallel between 

 the two great classes — decidedly leaves the Orthoptera and approaches 

 the Coleoptera. This is still more strikingly the case in Halictopha- 

 gus, which, in place of the weak and scarcely discernible nervures of 

 Stylops, has them strong and well marked : one of these, running pa- 

 rallel to the costa and situate immediately below it, is interrupted at 

 three-fourths of its length, thus enabling the wing to fold transversely 



