396 



PSYCHE. 



[July iSgb 



spines disappear and the scales begin. 

 Tlie points of the spines are raised at 

 an angle of about 45° and directed 

 obliquelv away from the edge of the 

 wing. Fig. 2, is taken from the edge 

 of the patch on the left wing of Fig. i, 

 and shows both the spines and border- 

 ing scales in their relative size and posi- 

 tion in relation to the wing. Fig. 3 

 is a lateral view of the spines as seen 

 from the edge of a fold through the 

 spinv area. 



On the thora.v the area is of similar 

 form and size, with clearly defined 

 boundaries and is located on the meta- 

 scutum at the. base of the abruptly 

 raised meso-scutellum. See Fig. i, Sj, 

 and Fig. 4, Sj. The area on the thorax 

 is slightly raised and flattened and has 

 no scales. The spines which cover 

 this area are precisely like those 

 on the wing and are so directed as to 

 point opposite or nearly opposite to 

 them when the wings are closed. The 

 spiny area when present occurs in both 

 sexes, even on the thorax of the apterous 

 females of the species of Orgyia. In 

 the microlepidoptera, so far as has 

 been observed, the spines both on tlie 

 vving and thorax are much farther apart 

 than in the Macros. 



So far as is known the Rhopalocera 

 do not possess these structures. There 

 is, however, on the fore wings of butter- 

 flies a patch of modifietl scales which 

 are pointed and elevated, but the patch 

 is of irregular shape and has no definite 

 boundary. In some it is very apparent 

 (Anosia plexippus Linn.) while in 

 others it is obscure ( Pieris rapae 



Linn.). The scales are often smaller 

 than the general type of scales of the 

 wing, but they are much larger than 

 the spines of the Heterocera. There is 

 no corresponding area on the thorax 

 but on the hind wing the scales near 

 the base of the costa are similarly modi- 

 fied. Fig. 5 shows one of the modified 

 scales fiom A. plexippus and Fig. 

 a noimal scale from the same wing. 

 Figs. 7 and 8 are respectivelv the same 

 from Heodes hypophlaeas (Bdv. ) 



In A. plexippus the modified scales 

 are so directed that those on one vving 

 cross those on the other at an angle. 

 If the two detached wings be held in 

 their natural relative positions the scales 

 of the two areas perceptibly interlock. 

 It is possible that these scales assist the 

 wings in making a uniform movement. 



It is an interesting tact that some, at 

 least, of the Trichoptera possess similar 

 spinv structures. They are nor, how- 

 ever, so well marked as in the Hetero- 

 cera and in some cases (Leptocerus sp.) 

 thev are very indistinct or absent. 

 Nettronia stygipes Hag. and Neuronia 

 semifasciata Say have them well 

 developed, both on the wings and 

 thorax. The most important difference 

 is that in the Trichoptera the spines 

 gradually change to the ordinary slender 

 spines, which cover the whole remain- 

 ing surface of the wings and body. 

 Fig. 8, shows the location of the patch 

 on the wing of Neuronia and Fig. 10, 

 shows the spines enlarged. Owing to 

 a lack of duplicate material in this order, 

 only a few species have been examined. 



In the Hymenoptera, I have found 



