EXTERNAL ANATOMY. 341 



teeth around the edge of the flattened surface (Plate 51, 

 Figs. 6 and 7). On one of the hind legs of the male, at the 

 end of the tibia, was found an additional appendage on the 

 side opposite to the spurs (Plate 51, Fig. 8). This is the 

 only monstrosity we have thus far seen in the gypsy moth. 



The wings differ somewhat in form in the two sexes, the 

 fore wings of the female being longer and more pointed 

 than those of the male. The venation is shown in Plate 52, 

 Figs. 1 and 2 (male), 3 and 4 (female). The frenulum at 

 the base of the hind wing of the male consists of a single 

 pointed bristle, while in the female it is composed of a clus- 

 ter of much finer pointed bristles (Fig. 4). The surface of 

 the wings is sparsely covered with scales and hairs (Fig. 7), 

 and around the outer border of both the fore and hind wings, 

 at quite equal distances apart, is a row of blunt spines, two 

 of which are shown in Fig. 8, and one still more enlarged 

 is represented in Fig. 9. These spines appear to be hol- 

 low, with a fine aperture at the outer end. Near the hinder 

 margin, towards the base of the fore wing, is an oval area 

 (Plate 52, Fig. 5), the surface of which is covered with 

 minute stout spines (Fig. 6). The lateral surface of the 

 metascutum (Plate 51, Fig. 1 ^) is covered with a similar 

 series of spines. 



In the "Berliner Entomologische Zeitschrift," Yol. 

 XXXI, 1887, Dr. W. Donitz describes a singing Lepi- 

 dopteron. After referring to the list of Lepidoptera which 

 produce sounds, given by Swinton in his work on "Insect 

 Variety," he describes an apparatus which he discovered in 

 Dionychopus niveus Men., a Bombycid moth found in Japan, 

 and also in Siberia. He states that when a fresh male is held 

 in such a manner that the wings can be moved back and forth 

 on each other, one can hear a slight chirping sound, which 

 continues as long as the wings are moved. He figured and 

 described an apparatus, on the basal part of the fore wings, 

 similar to that described above ; and a corresponding area on 

 the hind wings, where that of the fore wings overlies this 

 organ on the hind wings. In the gypsy moth no such organ 

 exists on the hind wing, but its counterpart is found on the 

 side of the metathorax, as stated above, where the organ in 



