XCl 



The scent-organ op certain mimetic Castniidae.— 

 Dr. K. Jordan exhibited some species of Castniidae which 

 resemble butterflies, and said that these mimetic Castniids 

 fall into two groups, each characterised by certain details 

 in the neuration and the colouring of both sexes, and by very 

 conspicuous differences in the development of secondary 

 sexual organs in the ^,^. In the one group (C. Units, C. zagraea, 

 C. carilla, etc.) the paronychium of the midtarsus of the ^ 

 is enormously enlarged, and there is no abdominal scent- 

 organ. In the other group (C. melessus, C. amazonica, C. 

 cycna, etc.) the first two abdominal sterna of the (J have a 

 large scent-organ on each side, which he described in detail. 

 The organ produces a substance which (in the dry specimens) 

 looks like grey or blackish mud and forms a thick coating 

 nearly over the whole ventral and ventrolateral surfaces of 

 the abdomen. The scaling on the innerside of the hindtibia 

 and hind tarsus of these q^ has developed into a pale brush. 

 The paronychium of the midtarsus is not enlarged. 



Sexual Dimorphism and Mimicry in Geometrids of the 

 Genus Bordeta Walk. — Mr. Louis B. Prout, on behalf 

 of Mr. J. J. JoiCEY, exhibited species of the Bordeta lemnia 

 group, together with their supposed ?$, and specimens of 

 Eucharidema for comparison, and read the following notes : — ■ 

 Recent careful examination has convinced me that there 

 is extraordinary sexual dimorphism in the group of '" Bordeta" 

 of which lemnia Bdv. (" Voy. Astrolabe, Fn. Ent. Pacif." i, 

 207, t. 5, f. 7, 1832) is the longest-known species. This form, 

 not very rare on Amboina, and recently collected (two ^<^) 

 by the Pratt brothers in Central Ceram at about 3000 ft. 

 altitude, is invariably ^. A very different-looking insect 

 from the same localities and always $, " Craspedosis (?)" 

 bicolorata Warr. (Nov. Zool. iii, 398), was collected by the 

 Pratts in three examples. The more blurred white markings 

 (as compared with the allies) is a feature common to the two, 

 while " bicolorata " retains an orange, black-belted posterior 

 half of the abdomen beneath as a further indication of its 

 ancestry, and close investigation reveals other points of 

 contact with lemnia. 



B. posticigutta Prout (Bull. Hill Mus. i, (2), 291), from higher 



