THE ENTOMOLOGIST. 277 



the cupule is curiously striated longitudinally. Figure 18, 

 which Dr. Mayr considers to be produced by Cynips Kollari, 

 I have always supposed to be, and have therefore called, 

 Lignicola; it is the one to which I have devoted more 

 attention than any other: in this the acovn-form is entirely 

 lost, the gall being perfectly spherical, a form which presents 

 to the superficial observer the most obvious objections; in 

 these, however, the projecting style was obvious in ninety- 

 seven galls out of a hundred which I examined ; in the 

 remaining three it was to be detected, but was not distinctly 

 pronounced ; it is always exactly opposite the basal attach- 

 ment of the gall : the exterior surface of the gall is scarcely 

 distinguishable from that of the pericarp of a perfectly healthy 

 and natural acorn, but the interior surface of the pericarp adheres 

 to the testa, and this to the cotyledons, thus causing a much 

 greater appearance of continuity than is the case in an acorn : 

 the cupule is very disproportionate in size, very much smaller 

 than in the normal acorn; sometimes, although rarely, the 

 testa, or its homologue, is separable both from the pericarp 

 and the cotyledons. In the galls produced by Cynips 

 glutinosa (Mayr's figures 21 a, 21b, 21 c, and 21 d) the con- 

 test between oak and Cynips seems to have been severe : the 

 form of the pseudohalanus is varied ; of its numerous shapes, 

 the acorn-shape being the exception. In the beautiful gall 

 produced by Aphilothrix Gemmaj (Mayr's figure 28), the 

 scales of the involucre, or cupule, are flattened and produced 

 into leaf-like laminae, forming an imbricated mass of very 

 interesting appearance: this curious object is usually called 

 the " artichoke gall." The minute, but perfect, representation 

 of an acorn in the centre of its leafy cup is very striking, and 

 I think must be convincing evidence of the truth of the 

 theory, so far as this species is concerned. The similarity of 

 the gall of Aphilothrix Glandulce of Hartig (Mayr's figure 34) 

 to an acorn seems to have impressed itself on that eminent 

 Hymenopterist, or he would scarcely have given it that 

 specific name. The same observation applies to the gall 

 produced by Spathegaster glandiformis of Giraud (figure 91 

 of Mayr)! 



In conclusion, I may say that I quite expect and hope to 

 hear objections to the theory here propounded, that many of 

 the oak-galls are pseudobalani, or false acorns, that is to say, 



