THE ENTOMOLOGIST. 



27 



It is generally about the size of, and has very much the 

 appearance of, a large gall of Cj'nips lignicola. At first it is 

 greenish, but when mature of a yellowish clay-colour, some- 

 times almost black. It is sprinkled all over with small 



Fig. 06. — Gall of Synophus politus. 



whitish warts, and covered with short hairs, which are only 

 visible with the aid of a magnifying-glass (sometimes the 

 base, which generally retains the bud-scales, is fixed to, and 

 grown into, the branch). At the point opposite the base 

 either a small umbilicate cavity or a small conical tubercle 

 is often found. The section shows that the gall consists of 

 two layers : the exterior one is green when fresh, and consists 

 of bark substance ; the interior one, however, which contains 

 the larva-cell, is formed of true wood substance. As the 

 second variation, I might mention that form which bears 

 crippled leaves on its surface, but in all other respects 

 perfectly agrees with the former variety. From this second 

 variation a third form is very often developed : in this case 

 the gall appears to have so long a continuity that it could 

 easily be mistaken for a mere swelling of the stem (con- 

 sequently it does not look like a bud-gall) ; this delusion is 

 all the more easy if the fly is not developed the first year, and 

 the following year the gall continues to grow as a twig. A 

 fourth variety is interesting on account of the constancy of its 

 size and shajie ; we often meet with an oak on which we only 

 find this variety in great numbers: it is spherical, and is 

 about five millimetres in diameter; the small white warts are 

 wanting, or are far less conspicuous than in the first-described 

 form ; the umbilic or conical projection at the top is also 

 wanting. In section it exhibits a much thinner layer of bark 

 and wood substance, while respectively the larva-cell is very 



