TORTMIPiE. 29 



replaced in a few species by blue or by purple, or by reddish cupreous. 

 When a reddish or yellowish hue appears it is only on the abdomen, 

 where it forms a band or occupies tbe basal part. 



C. nigricornis perhaps is brought up exclusively in oak-apples, and 

 its long oviduct is exactly adapted to the probing of these from the 

 outside to the middle, and when it (the next generation) has emerged 

 thence in its perfect form, and is about to seek a suitable place for 

 its eggs it resorts to a more recent oak-apple by instinct. When the 

 oak-apple has attained its full size the grub in the middle of it is 

 only accessible to C. nigricornis, but when the oak-apple is of small 

 size this grub is liable to the attacks of other species of Callimome. 

 Some species of this genus dwell both in oak-apples and in other oak- 

 galls, and having comparatively short oviducts they limit their egg- 

 laying to the more or less superficial inhabitants of the oak-apples. 

 These have the choice of two means of bringing up the ensuing 

 generation, and when they leave the old oak-apples and cannot find 

 convenient fresh oak-apples they may resort to the oak-currants, and 

 when they take wing from the oak-currants and can find none of that 

 year's growth they may fly to the oak-apples. It will be said that 

 when both ways of subsistence are equally attainable, the flies from 

 oak-apples will select oak-apples, and those from oak-currants will 

 prefer oak-currants by " the law of inheritance." 



The European species of Calhmome, with a few exceptions, are 

 included in the following Synopsis :-=»■ 



A. Oviduct more than twice the length of the body. 



a. Abdomen not blue-aeneous. - - nigricornis, Fabr. 



b. Abdomen blue-aeneous. - - cyaneus, Fons. 



B. Oviduct a little less than twice the length 



of the body. ... - saphiriuus, Boh. 



crinicaudis, Ratz. chalybaeus, Ratz. 



C. Oviduct longer by half than the body. 



a. Abdomen pale at the base. - - cynipedis, Linn. 



b. Abdomen not pale at the base. 



* Body blue. .... azureus, Boh. 



** Body green. - quercinus, Boh. 



*** Body cupreous. ... speciosus, Boh. 



D. Oviduct longer than the body. - - Devoniensis, Parfitt. 



annulatus, Spin', macrocentrus, Ratz. 



E. Oviduct a little longer than the body. - elegaus, Boh. 



Forsteri, Ratz, Lasiopterse, Gir. 



F. Oviduct hardly longer than the body. - Druparum, Boh. 



G. Oviduct as long as the body. 

 a. Abdomen pale at the base. 



