190 



very easily distinguishable in form, by the pigmented, sometimes 

 deep crimson-colored, granular contents, which mark out differ- 

 ent areas. (PI. XPII fig. 4.) Shortly 'before hatching, the pupa 

 appears more uniformly yellow, owing to the color of the adult 

 insect, shining through the thin, translucent pellicle. In about 

 twenty days from oviposition the adult parasite emerges from 

 the egg-chamber of the leaf-hopper. 



In this and other species of Poranagnis the winged parasite 

 escapes through the scar made by the leaf-hopper ; but some 

 species of Aiiagnts, parasitic on the same eggs, and very similar 

 in general appearance to those of the above named genus, never 

 do so, but always gnaw a distinct round hole, in order to leave 

 the egg-chambqr- Such too is the habit of Polyncma rediivioli, 

 which often emerges at quite a distance from the free extremity 

 of the imbedded egg, in which it was bred. (PI. XIII, fig. 7.) 



The habits of the two egg-parasites that are commonly found 

 together in the cane fields are also in some oither respects strong- 

 1}' contrasted. The Paranagrus has a particular liking for the 

 egg-chambers placed at the bases of the mid-ribs (where in fact 

 they are most numerous) though it will attack those in any 

 situation. The Anagrus on the other hand greatly prefers those 

 on the higher parts of the mid-rib and more particularly on the 

 edges of this, where the lamina of the leaf ijoins it. Very rarely 

 does it attack the eggs at the base or in the centre of the mid- 

 rib, unless in the case of very young cane leaves. 



The species of Anagrus and Paranagrus here dealt with are 

 habitually parthenogenetic, the males only appearing at inter- 

 vals, and then in very small numbers, as compared with the 

 females. In breeding a species of the latter genus continuously 

 from January to September, a fresh brood appearing every three 

 weeks, it was not until the middle of the latter month that the 

 first males appeared. During the time specified very many thou- 

 sands of individuals were examined, and the males, it should be 

 added, can easily be distinguished from the females by anyone 

 familiar with the species, without the aid of a lens. The case 

 of the Anagrus is similar, as far as the species we have studied 

 are concerned. One may in fact regard the species of these 

 two genera as far advanced on the road towards perfect par- 

 thenogenesis. 



CLASSIFICATION. 



ITaliday, who perhaps studied these atoms of insects more 

 carefully than other hymenopterists, as early as 1833, assigned 



