The Zoologist — January, 1871. 2435 



" 2. Isosoma grnminicola, Givaud. The pavticulavs given of the 

 larva of the preceding species apply also to the larva of this 

 Isosoma. It grows and undergoes its transformations at the same 

 time. At whatever age I have observed it, I never met with a 

 victim near it, and it appeared to me evident that it also drew 

 its nourishment from the plant, at least during tlie greater part 

 of its growth. This mode of life is in contrast with that of 

 larvae of the genus Eur^toma living in the galls of Cynips, for 

 the latter are constantly zoophagous, and may be found fixed 

 on the body of their victim the whole time that they require 

 food. 



"3. Isosoma lineare, Walker. I obtained only a small number 

 of females of this species which is much more rare than the pre- 

 ceding one in the galls of Triticum vepens. I did not distinguish 

 its larva, which doubtless closely resembles the preceding and lives 

 under the same conditions." 



The following relates to a new species of Isosoma which 

 Dr. Giraud reared from a Festuca :— 



^^ Isosoma sociabile, Giraud. In a somewhat thin piece of the 

 stalk of a grass, the species of which has not been ascertained with 

 certainty, but which very probably belonged to the genus Festuca, 

 I found, in the month of March, assembled at one part of the tube, 

 eight larvae like those of Isosoma graminicola. The space they 

 occupied, rather less than a centimetre in length, was not marked 

 with any stain, but the medullary membrane had disappeared, at 

 this spot, whilst all the rest was in a normal state. After having 

 examined them, I closed their dwelling by re- adjusting the bits of 

 straw which had been displaced and retaining them by a ligature. 

 Impatient to see what they had become, I again opened the haulm 

 in the month of May, and found four individuals of this species, 

 alive and already escaped from the pellicle which covered the 

 nymph, with the exception of the antennte which retained their 

 covering. The other larvae had perished. In this case, also, 

 I could not discover any trace of victim, and it appeared to me 

 evident that the larva? must have drawn their nourishment from the 

 substance of the plant, as' we have seen in the case of Isosoma 

 graminicola; but with this difference that they lived in society, 

 whilst the others were solitary. One is inclined to think, after 

 these observations, that these insects are not parasites j but their 

 systematic position and their atfinity to the Eurytoma?, which 



