1921] Wells — Neiv United States Zobcecidia 39 



wall thin, similar to leaf in texture though slightly thicker than 

 leaf; few on any one plant. Martin Co., Ind. Types in collection 

 of writer. 



This gall was collected by Mr. Chas. C. Deam, to whom I am 

 indebted for its study. 



Gleditsia. 

 Cecidomyia sp. Cecidium nov. Fig. 10. 



10. On Gleditsia triacanthos L., leaf rachis; kataplasma; sim- 

 ple elongate swelling of leaf rachis, commonly the secondary axes, 

 5-10 mm. long, about 1 mm. dia., surface same as normal rachis; 

 monothalamous, the chamber a mere capillary tube; not uncommon, 

 Toledo, 0. Types in collection of writer. 



Grindelia. 

 Cecidomyia sp. Cecidium nov. Fig. 11. 



11. On Grindelia lanceolata Xutt. (Eosin weed), a modification 

 of the floral head; kataplasma, rosette type; a mass of overlapping 

 involucral bracts (each external bract much thicker than normal 

 ones), the whole assimiing an ovoid shape, 2,4—3,5 cm. long; single 

 chamber at center surrounded by much reduced bracts, elongate - 

 ovoid; one or few galls on single plant, infrequent; Fayetteville, 

 Ark. Types in collection of writer. 



The characteristic salmon-covered larva of the Itonididae with 

 breast-plate was found in the galls. 



Fig. 11, left, shows a normal head and a galled one; right, sec- 

 tion of affected head. 



Grindelia. 

 Cecidomyia sp. Cecidium nov. Fig. 12. 



12. On Grindelia squarrosa (Pursh) Dunal, bud gall; kata- 

 plasma ; sub-globose with attenuate tip or tips representing aborted 

 leaf elements, 5-8 mm. dia., green, very prominent in axils of 

 normal leaves, 1-4 chambers, each elliptical in outline, walls thick 

 of firm, fleshy texture; not common, Manhattan, Kan. Types in 

 the collection of writer. 



Hedeoma. 

 Cecidomyia sp. ( ?) Cecidium nov. Fig. 13. 



13. On Hedeoma pulegioides (L) Pers. (Pennyroyal), a simple 



