340 Transactions of the Canadian Institute [vol. ix 



Andricus piger Bassett. 



Andricus petiolicola Bassett. 



Andricus (undescribed). 



Rhodites muUispinosus Gillette. 



Rhodites lenticularis Bassett. 



Rhodites ignotus O.S. 



Rhodites bicolor Harr. 



Rhodites gracilis Ashm. 



Rhodites nebulosus Bassett. 



Cynips? constricta Stehbins. 



Solenozopheria vaccinii Ashm. 



Aulacidea nabali Brodie. 



Neuroterus majalis Bassett. 



Aylax glechomcB Linn6 (referred to the section on Cytology). 

 Holcaspis globulus Fitch. 

 Host Quercus alba L. 



A monothalamous, spherical gall produced at the nodes of the stem 

 of the host. 



It occurs singly or in groups of from two to four. The colour is yellow- 

 ish-green usually with a reddish tinge. When mature the oval larval 

 chamber is free from the remainder of the gall. The aperture of exit of 

 the producer is placed at the end of this larval cell. 



Dimensions: — Average diameter 13 mm. 



When this gall is so young that it is still soft, it has the following 

 anatomical characteristics. The larval chamber is in organic continuity 

 with the remainder of the gall. Beneath the small celled epidermis are 

 four or five layers of cells with their long axes parallel to the periphery 

 of the gall. Inside this tissue is the more typical part of the parenchyma 

 zone. Here the cells are in radial rows forming a fairly compact tissue 

 with only a few small air spaces. Their radial walls are more elongated 

 the nearer they are to the larval chamber. Inside of the parenchyma 

 zone is a poorly defined cambium^ tissue that passes gradually into a 

 crystal layer. Each cell of this zone contains a large crystal mass. A 

 second cambium tissue, in this case well defined, bounds the crystal 

 layer on the inside. From this cambium the nutritive layer is produced. 

 This consists of cells, almost square in outline, arranged in radial rows 

 (Fig. 65). 



The protective zone is differentiated only in the later stages of de- 

 velopment. It is found, however, when the gall is mature, forming the 

 entire wall of the free larval chamber and extending a short distance 

 beyond it. Its cells are of the usual sclerenchyma type with uniformly 

 thickened, laminated walls perforated by branched simple pores. 



