Dec, 1915] Zoocecidia on Species oj Hicoria 49 



A most interesting variant of this form is illustrated in 

 Fig. IGa. If it were not for the large number of intermediate 

 forms found, this one would easily be considered distinct. The 

 region of the chamber surrounded by thick walls has been much 

 reduced, so that only a circular area about the upper part of the 

 chamber has the thick wall projecting from it. This new con- 

 dition results in the formation of a definite saucer-shaped 

 structure on the distal end of the gall. In some specimens the 

 structure was no longer saucer-shape, but by the ingrowth of 

 the edges it was assuming a spherical form, developing a two- 

 chambered gall. It is natural to suspect that this may have 

 been the mode of origin of the four-double-chambered galls 

 described elsewhere in this paper. That, however, is entirely 

 problematic. 



17. Caryomyia periscoides Beut. 



On leaf, underside, generally large, sub-globular galls. 

 Younger ones appear like older, both often being found on same 

 leaflet, 4-7 mm. diameter. Galls covered with a fine short 

 yellowish to reddish pubescence, suggesting the texture of 

 peach "bloom." Walls very thick, firm fleshy, surrounding 

 the central spherical cavity, pierced, however, at the distal 

 end by the fine apical canal. Closely sessile on leaf, generally 

 at side of principal vein. Collected on H. alba, glabra and 

 ovata. 



From Felt's short description, Caryomyia antennata Felt, 

 must have been taken from a similar gall. 



Osten Sacken, Lowe's Mono. Dip. N. Am. Pt. I. p. 193. 1862. 

 Beutenmuller, Am. Mus. Nat. Hist. Bull. 23:393. 1907. 



18. Cecidomyia sp. 



On leaf, under side, sub-globular (almost uniformly asym- 

 metric in that one side projects laterally so as to present a 

 parabolic outline, rather than a semi-circular one). A short 

 definite nipple terminates the gall. 2-4 mm. diameter. White 

 or light yellow to red. Walls medium in thickness, of a soft, 

 almost fleshy consistency. Exterior surface almost uniformly 

 minutely shagreen-roughened when observed with lens. The 

 constricted base of the gall rests in a shallow saucer-shaped 

 structure. 



