﻿20 [June, 



closely allied to, and yet quite distinct from, those produced in June. Out of 

 thousands of these autumnal flies examined by us. all were females, with not a 

 single male among them; and we have experimentally ascertained, by colonizing a 

 number of these females upon isolated black-oaks known to be not previously 

 infested with oak-apples, that they cause apples to be generated in the following 

 spring upon such isolated oaks. From oak-apples produced in this manner we have 

 bred two specimens of the spring form (Q.-spongifica) of gall-fly which exists in both 

 sexes, and five specimens of the autumnal form (Q.-aciculata) which exists exclusively 

 in the female form. Finally, treating these five autumnal specimens in the same 

 manner, i. e., placing them upon another isolated black-oak, we obtained galls in 

 the following spring which produced two specimens of the spring form (Q.-spongifica), 

 thus showing that the autumnal form sooner or later reverts to the spring form. 

 Hence, as well as from other considerations, we may infer that the former is not a 

 distinct species, but a mere dimorphous female of the latter ; for otherwise one 

 form could not generate the other. The bastard oak-apple matures like the pre- 

 ceding in June, but is found exclusively upon the red-oak (Quercus rubra). It 

 differs from the preceding in never reaching so large a size, in the central cell not 

 being woody, but consisting of a mere shell which can be readily broken with the 

 thumb-nail, and in its being only connected with the external rind by slender 

 radiating filaments. Males and females (C. Q.-inanis) absolutely indistinguishable 

 from the spring form of the preceding species, are obtainable from this gall in 

 June ; but after repeated trials we have never succeeded in breeding from it a 

 single autumnal female, and we do not believe that any such form exists. Hence, 

 and also in consequence of the veiy great dissimilarity of the galls, and their 

 always growing upon distinct species of oak, we are compelled to consider these 

 two gall-flies as distinct species, although when placed side by side the forms 

 generated in the spring are always exactly like each other." 



Mr. McLachlan exhibited all the forms of a small species of Hermes brought 

 from St. Helena by Mr. Melliss, and being the same to the ravages of which, in 

 that island, Mr. Layard called the attention of the Society in 1866 (Trans. Ent. 

 Soc. 3rd series, vol. v, Proc. p. xii). Mr. Layard stated that the insect had been 

 introduced in limber from the Coast of Africa, but Mr. McLachlan could not 

 identify it with any described African species, and was inclined to consider it the 

 T. tenuis of Hagen, which inhabits the West Indies and Brazil. Considering that 

 St. Helena is a place of call for vessels from all quarters, there is no reason why it 

 should not have originated from the West ; though one would naturally look to 

 Africa as its home, and from this cause he was inclined to think that the idea of 

 its coming from thence had originated. It is an anomalous species in its structure, 

 in which it agrees with T. tenuis. Mr. McLachlan also exhibited a large number of 

 small black Podurce placed in his hands by Mr. Henry Lee, and concerning which 

 it was stated that they had been found at Hungerford, on the 10th April, on the 

 surface of a duck -pond, which they covered to such an extent as to give the idea 

 that a bag of soot had been emptied over it. 



Mr. A. E. Wallace read "Notes on eastern Butterflies (Biadema) ." 

 Mr. Butler read " Descriptions of a new or little known forms of Diurnal 

 Lepidoptera." 



