xxiii GALLS 533 



of the other, hardly showing any differences, except the strictly 

 generic characters ! This seems to be one of those curious 

 instances, so frequent in entomology, of the resemblance between 

 parasites and their hosts ! By rearing a considerable number of 

 galls of D. nebulosiis I obtained this species as well as its parasite 

 almost in equ.al ntimbers. By cutting some of the galls open I 

 ascertained that a single specimen of the gall frequently con- 

 tained both species, thus setting aside a possible doubt whether 

 these Insects are not produced by two different, although closely 

 similar galls." '■ 



The substance of which galls are composed, or rather, perhaps, 

 a juice they afford, is apparently a most suitable pabulum for the 

 support of Insect life, and is eagerly sought after by a variety 

 of Insects ; hence by collecting galls in large quantities many 

 species of Insects may be reared from them ; indeed by this 

 means as many as thirty different kinds of Insects, and belong- 

 ing to all, or nearly all, the Orders, have been obtained from a 

 single species of gall. Some galls are sought by birds, which 

 open them and extract their tenants, even in cases where it 

 might be supposed that the nauseous flavour of the galls would 

 forbid such proceedings. 



Not more than 500 species of Psenides and Inquiline Cyni- 

 pidae are known from all parts of the world ; and of described 

 Parasitic Cynipidae there are only about 150 species. The 

 British forms have recently been treated by Cameron in the 

 work we have already several times referred to.^ 



A few Cynipidae have been found in amber ; and remains of 

 members of the family, as well as some galls, are said by Scudder 

 to have been found in the Tertiary strata at Florissant. 



Fam. II. Proctotrypidae, or Oxyura. 



S-mcdl Hijmenoptera, ivith feiv, or even no, nervures in the wings : 

 the pronotum closely adherent to the mesothorax, and at the 

 sides reaching hackwards to the points of insertion of the 

 wings. The abdomen is pointed, and the pointed apex is 

 frequently defexed ; the ovipositor is not coiled, but is 

 retractile, and when extruded is of tubular form, and appar- 



1 F. ent. Soc. PMlad. ii. 1863, p. 34. 

 2 Brit. Phyt. Hym. vols. iii. and iv. Kay Soc. 1891 and 1893. 



