( cxiii ) 



There is an important group of Deltas, consisting of D. mysis, 

 D. argenthona, D. caeneus, and D. eucharis with the geo- 

 graphical forms D. stollii, hierte and hyjmrete, which is marked 

 off from the rest of the genus no less by the character of its 

 plume-scales than by its obvious aspect. The laminae in these 

 species possess the common character of a triangle with elon- 

 gated apex, so that their outline may be compared to that of 

 an inverted funnel or tru.mpet. In D. argenthona and D. 

 hyparete, the lamina, from its expanded and rounded base, 

 may pei'haps more aptly be termed decanter-shaped. The 

 apex in these species, though narrow, is blunt, and not filiform 

 as in the majority of the species of Delias. It is often later- 

 ally bent, and may be slightly twisted. The fimbriae, which 

 are rather short, are termino-lateral. The scent-scales in all 

 this group are very much smaller than those of most other 

 members of the genus ; the discs are large in proportion, 

 generally rounded, and in some species, notably D. caeneus, 

 well-displayed in consequence of the straightness of the 

 footstalk. 



As regards their scent-scales, Delias nigrina and D. ornytion 

 are in some ways transitional between the eucharis group and 

 the rest of the genus. Like the former, they have a triangular 

 lamina with a prolonged apex ; this, however, is acute though 

 not filiform. The lamina is much larger than in the eucharis 

 section, but still below the average size of the genus. A 

 curious feature in D. ornytion is the frequent presence, on 

 one lobe only of the somewhat cordate base, of a sharp spur 

 looking like a rudimentary form of such a spine as occurs in 

 " Ptycho2)tei'yx" lucasii. 



It is perhaps worth noticing that when I was investigating 

 the genus Delias from the point of view of colour-patterns, I 

 was inclined to consider D. nigrina as a term in the series 

 leading through D. harpalyce up to D. agani'p'pe. The evidence 

 of the scent-scales, without contradicting this, seems to in- 

 dicate an approach on the part of D. nigrina to the eucharis 

 group, as well as to that with which I formerly associated it ; 

 and seems also to show that its affinity with D. ornytion is 

 closer still. 



Next on our list comes the neotropical genus Pereute. The 



PKOC. ENT. SOC. LONU., V. 1909. M 



