48 THE ENTOMOLOGIST. 



diameters larger than the cavities into which the stems of the 

 wing scales are inserted. On the fore wings the bristles may be 

 observed near the base of the costal edge, and at regular 

 intervals along the costa, round the apex and the outer edge, to 

 near the extremity of the first cubital nervule ; there are none 

 beyond this point, nor on the inner margins of the fore wings. 

 On the hind wings, the first bristle may be observed at the 

 extremity of the first radial nervule, and they occur at regular 

 intervals to very near the anal nervure. 



The wing scales are of entirely different structures, and are 

 horizontal to the surface of the wing ; the fringe scales continue 

 the horizontal plane beyond the margin of the membrane. All 

 round the margin of each wing, the scales are inserted into 

 cavities, very close together, and there are at least three rows of 

 such parallel to each other. The bristles are so far removed 

 from the extreme margin of the wing that they are inner to the 

 second row of scales, and between each of the bristles, according 

 to the distance apart, there are from nine to twenty-one scales in 

 each row. The bristles are wider apart on the costal margin 

 than they are on the outer margin of the wing. 



Many species of Geometrae — Boarmia repandata, Hyhernia 

 leucophearia, CJieimatobia hrmnata — rest with wings expanded, 

 and touching the surface of tree trunk, branch, paling, or what 

 not, on which the insect may be during day-time ; but observe 

 these same insects at night, either settled or in copulation, and 

 the wings are erect. I have seen them so during the day-time, 

 and remember, on at least one occasion, speculating as to why 

 the erected wings were not blown apart by the strong wind which 

 was blowing direct on to the edges. I would now suggest — in 

 fact, it seems obvious — a function of the marginal bristles is that 

 of fastening together the edges of the opposite wings when they 

 are erect. It is probable that the normal action of the muscles 

 at the base of the wings is to expand them, and the ability to 

 keep them erect is largely helped by the marginal bristles. 



Noctuae — Ortliosia macilenta, Caotcala nupta, Mamestra bras- 

 sicce — have the marginal bristles. Mamestra {Melanchva) mutans 

 (N. Z. sp.), which I have just examined, has stronger bristles, 

 with a more pronounced curve, than most Geometrae ; in Noctuae, 

 however, the marginal bristles rise from the under surface of the 

 wing. Clearly, the function ascribed to the bristles among 

 Geometrae does not apply to the Noctuae. Here is a problem 

 which I will leave to anyone who feels sufficient interest in the 

 subject, and will merely remark that the marginal bristles occur 

 in both male and female of Asaphodes megaspilata, and is probably 

 not a sexual character. 



Palmerstou North, New Zealand : Sept. 1st, 1900, 



