'2-24 



THK KNTOMOLOGIST. 



DeGeer, Reauniur, Linne, Fabriciiis, &c., the most important 

 memoirs are Hartig's, in Germar's ' Zeitsciirif't,' ii. 176 — 209 

 (1840), iii. 321— 358 (1841), iv. 395— 422 (1843); Giraud's, 

 in ' Veihandlungen, z.-b. Gesellschaft, Wien.' ix. 337 — 374 

 (1859); Schenck's, in ' Beitr. z. Kennluiss. d. nass Cyn.' 

 (1865) ; and Schlechtendal's, in the 'Steltiner Entomologische 

 Zeitung,' xxxi. 338—347, 376—398 (1870); but very many 

 smaller and scattered papers must be referred to. Those by 

 Osten-Sacken, Walsh, and Bassett, in the first four volumes 

 of the Proceedings of the Entomological Society of Phila- 

 delphia, are important. A series of papers on the British 

 species, by the Rev. T. A. Marshall, appeared in Ent. Mo. 

 Mag. (1867 — 8): in these fourteen oak species are described 

 as British ; we now know forty-one to be indigenous. This 

 shows that good work has been done. 



A general enquiry has been — how to distinguish the 

 inquiline Synergi from the true gall-makers? This may be 

 at first rather confusing; but perhaps the best general guide 

 that can be given is the venation ol the fore wings. The two 



S. FACIALIS. A. CURVATOR. 



((, h, c. Areola radialis ; c, d, <■. Areula cubitiilis secunda. 



accompanying figures show ihe difference clearly. The gall- 

 makers have the second cubital areola (t*, d, e, in figure) at 

 the base of the radial cell (a, c, b, in figure), whilst the Synergi 

 have it near the middle. The first section — Hartig's " area 

 radialis angusta, areola basalis" — is represented by a wing of 

 Afidricus curvator. Hart., and the inquiline — Hartig's "area 

 radialis brevis, lata; areola intermedia" — by a wing of 

 Synergus fdcialis. Hart. 



It is amongst the Hymenoptera, especially the gall-making 

 species, that some of the most interesting and astonishing 

 problems in insect biology are to be worked out. In 

 gall-makers we have the formation of the gall : the 

 active agent, its development, the life-history of the gall- 

 fly, and the other insect life, — normal, inquiline, or ))ara- 

 silic, — which is also connected with the gall. Of each 



