April, 1904.] Galls and Insects Producing Them. 141 



mature, but the cells lining the larval chamber were well supplied 

 with protoplasm, and numerous short trichomes were developed 

 from the dorsal surface and extended into the chamber. Tannin 

 was very abundant. 



The gall of Cecidomyia tubicola O. S. on Hicoria ovata (Figs. 

 1 17a, b, c) is very similar to C. holotricha, except that the amount 

 of tannin is not so great. The upper wall of the gall is much 

 thicker than either the side or lower wall. The point of attach- 

 ment is not so large, but the gall is protected by a growth pro- 

 ducing a cup-shaped cavity in which the gall is developed (Fig. 

 117a). The inner layers of cells are very rich in protoplasn). 

 The cells are elongated in the long axis of the gall and fibro- 

 vascular bundles are more numerous than in C. holotricha, but 

 are very small. The cup- shaped structure (117c) in which the 

 gall is formed is composed of elongated cells. The palisade cells 

 in that part of the leaf opposite the gall are unaffected. 



Cecidomyia viticola O. S. (Fig. 118) has the same general 

 character as C, tubicola, but is much longer. 



Sciara ocellaris O. S. is one of the simplest of the Cecidomyidae 

 galls. The larva does not penetrate the tissues of the leaf, but 

 confines its attack to the outside, causing an indentation on one 

 surface of the leaf and a corresponding elevation on the opposite 

 surface (Fig. 119a) and also causing a very slight thickening. 

 The structure (Fig, 1 19c) when compared with that of the normal 

 leaf (Fig. 119b) shows the palisade transformed into ordinary 

 mesophyll and the intercellular spaces entirely obliterated. It 

 therefore corresponds in structure to the simple leaf-curl galls 

 produced by some of the Aphididae (e. g., Schizoneura Ameri- 

 cana Riley, Part i, Fig. 12). 



3. GALLS OF THE CYNIPIDAE. 



My specimens of Rhodites bicolor Harris (Fig. 120) were well 

 developed when collected. I was therefore unable to determine 

 the early structural characters. The structure in these galls evi- 

 dently does not show the four well defined zones so characteristic 

 of this family. The inner cells are well supplied with nourish- 

 ment for the large number of larvae. 



The galls of Amphibolips confluentus Harris are very large and 

 have a single larval chamber in th'/ center. The nutritive and 

 protective zones (Fig. 12 ta) can be distinguished, but are not so 

 well defined as in the closely related species, A, inanis (Part I, 

 Figs. 28a, b). The parenchyma and epidermal zones (Fig, 121b) 

 are well defined and the space in the parenchyma is filled with a 

 cottony-like substance which upon close examination is composed 

 of fibro- vascular bundles (as in A. inanis, Figs. 28a, b, and H. 

 centricola. Figs. 27a, b, c) and of long, unicellular threads (Fig. 

 i2ic), as in C. papillatus (Figs. 30a, b, c and 81). 



