Biology of the Membra cidae of the Cayuga Lake Basin 329 



seems to be no reason why they should not be so used since they are 

 apparently constant within a species and differ in appearance within 

 a genus. The basal and costal areas of the wing are inclined, also, to be 

 coriaceous, punctured, pubescent, or opaque. These features arc com- 

 monly used as specific characters, and in some cases (Van Duzee, 1908 a : 55) 

 as generic. In one subfamily, the Tragopinae, the fore wings are so dense 

 and coriaceous that the veins are scarcely distinguishable. This character, 

 indeed, is generally given as distinctive for this subfamily. 



The hind wing (Plate xxxiv, 11) is similar to the fore wing in position 

 and attachment. It rests partly on the dorso-caudal extremity of the 

 metathoracic episternum, and is attached by strong muscles which extend 

 into the body cavity just below the metanotum. The anal lol)e is folded 

 under the remainder of the anal area when the insect is at rest, as indi- 

 cated by the dotted lines in the figure. At the base of the anal region 

 is a strong hook, which is generally constant in appearance but the function 

 of which is not evident. The caudal margin of the metanotum shows 

 in some species an overhanging flap which engages the wing when folded. 



No axillary sclerites have been found in the hind wing. From this fact 

 it might be well to question the correctness of the interpretation of the 

 structures described in the fore wing as axillaries. There is little doubt 

 that the hind wing in the Membracidae is more generalized than the fore 

 wing, and one would naturally expect to find in the more generalized 

 wing the better evidence of primitive structures. The fact that such 

 structures cannot be found would indicate either that the axillaries are 

 not primitive in the family or that the thickenings in the fore wing are 

 not true axillaries. The latter theory is perfectly tenable, since, as has 

 been remarked in the discussion of these structures, their validity as 

 chitinized sclerites may well be doubted. It is true that the full comple- 

 ment of axillaries has been recorded for other Hemiptera (Snodgrass, 1909 : 

 594) , but here again the forms studied belong to the Heteroptera. A study 

 of the alary and the pedal apparatus would seem to indicate that the 

 relationship between the Heteroptera and the Homoptera may not l^e so 

 close in respect to locomotion as in other respects, and the presence of 

 the sclerites in the former suborder need not necessarily presuppose their 

 existence in the latter. In fact one or two orders, notably the Ephemerida 

 and the Odonata, have thus far failed to show axillary sclerites and it would 

 appear that the Homoptera might be grouped with these orders in this 



