6 Mr, H. Eltringham's Monogra/ph of the 



from a point at the end of the coll. The scales are nor- 

 mally of uniform size and nearly round. In those species 

 which exhibit transparency of the wing, this result is 

 attained by a variety of different methods. The scales 

 may be reduced in width, may be mere hairs, may be 

 normal in size but reduced in number, normal in size but 

 raised up so as to allow the light to pass between them, or 

 they may be absent altogether. In a few species large 

 special scales are found on the median nervure on the 

 underside of the fore-wing. The antennae are short and 

 rather abruptly clubbed. The male genital armature 

 varies from a state of extreme complexity to one of primi- 

 tive simplicity, but in the majority of species exhibits 

 little individual variation. In most if not all species 

 special scales are found attached to the underside of the 

 last abdominal tergite. These scales are soinetimes 

 present in enormous numbers. They are ensily detached 

 and may be scent-producing organs. The female 

 usually jjossesses a chitinous plate on the seventh sternite 

 surrounding the external oritice of the bursa co])ulatrix. 

 The f )rm of this plate is specifically constant in most 

 species. Those females which possess such a plate have 

 upon it after pairing a hard wax-like structure (see p. 7), 

 often containing scales and hairs from the body of the male. 

 The larvae * have two dorsal, two lateral, and two sub-lateral 

 rows of branched spines, and the pupae are white or 

 whitish with ])lack spots, often in the form of rings 

 enclosing yellow or pink centres. The neuration of the 

 wings and the position of the other appendages are more 

 or less outlined in black on the pupal skin. In many 

 cases the pupa bears short blunt spines or processes, but so 

 far as is known never has long hooked spines as in Plancma. 

 The genus Acraca is almost confined to the Ethiopian 

 region. In the Oriental region there occur four or perhaps 

 five species, according as to whether wo regai'd A. mcycri 

 and A. moluccana as one species or two. Of these A. vesta 

 is interesting as appearing to be closely allied to the 

 African A. anacrcon. A. amtromaclie, which extends into 

 the Pacific Islands as far as Samoa, shows in the structure 

 of the male armature a close alliance with A. ir/ati from 

 Madagascar. I have dealt with the probable .synonymy of 

 the Oriental s])ecies in the Supplement to the present 

 monograph. 



* See F. MiiUer, .Stettin Knt. Zeit,, 38, p. 492, etc. (1877). 



