SOME UNDESCRIBED RHOPALOCERA FROM SIAM. 175 



Nymphalinve. 

 6. Penthema darlisa melema, asp. nov. 

 ( Plate V, fig. 1. ) 

 d. Very similar to typical darlisa, but smaller, the white 

 markings of forewing and the straw-coloured markings of hind wing 

 slightly reduced in size, especially the latter. The bluish suffusion 

 of forewing less pronounced, giving the insect a much browner ap- 

 pearance. The underside shows a corresponding difference. 



Length of forewing. — 55 mm. (the Type of darlisa measures 

 67 mm.). 



B. M. Type No. Rh. 122, cJ- Me Song forest, Prae, N. Siam ; 

 April 1918. 



This race should be readily recognisable by the characters 

 given. The reduction in size of the lighter markings is particularly 

 noticeable in the basal half of the hindwing. It was obtained in 

 some numbers in the Me Song forest, during April 1916 and April 

 1918. 



7. Penthema binghami mimetica Lathy. 

 (Plate V, fig. 2.) 



Penthema mimetic./, Lathy, Entomologist, xxxiii, p. 213 (1900). 



P. d irlisa mimetica, Fruhstorfer, in Seitz Macro-lep., ix, p 464 (1912). 



P. mimetica was described by Lathy from a single female 

 which came from Pak Jong, Central Siam, and which is now in the 

 Adams Coll. in the British Museum. A second female was obtained 

 at Hup Bon, S. E. Siam, in April 1914 and since then a number of 

 males have been taken in the Me Song forest, Prae, N. Siam. 



Fruhstorfer ( I. c. ) regards mimetica as a form of P. darlisa 

 which he treats as a species dimorphic in both sexes. An examina- 

 tion of the genitalia of these two forms, P. d. melema, and P. b. 

 mimetica, however, entirely contradicts this view. Though super- 

 ficially alike, actually these structures are very distinct in the two 

 forms. In each species the uncus terminates in a long spike directed 

 downwards almost at right angles to the long axis of the body. 

 Slightly proximal to this there arises a pair of spines, not very close 

 together, and running parallel to each other and to this terminal 

 spike, their tips directed posteriorly. In melema these are very 



VOL. IV, NO. 3, 1921. 



