No. 2368. AMERICAN SUBTERRANEAN GALLS ON OAK— WELD. 191 



3. Cells in thickened bark at crown of tree. 



Occurring in large numbers forming swollen areas in the bark: 

 On main roots of trees of Q. alba, prinus. 



21. Callirhytis futilis (Osten Sacken) (agamic generation), p. 221 . 

 On main roots of tree or where bending limbs touch ground. Q. chrysolepis. 



17. Callirhytis hartmani Weld, p. 214. 

 At base of sprouts or saplings. Q. macrocarpa. 



32. Compsodryoxenus illinoisensis Weld, p. 234. 

 Small cells in swollen and distorted bases of sprouts. Q. breviloba, stellata. 



13. Xystoteras contorta Weld, p. 209. 

 Thin-walled, nested cells in one-sided gradual swelling on small shoots of Q. 



fendkri See No. S3, p. 235. 



Similar but on Q. gambelii and adults in spring See No. SO, p. 232. 



Occurring in groups of less than a dozen usually, sometimes single: 



Ellipsoidal cells protruding abruptly from the bark in rows or groups or single 

 and detachable, sometimes confluent, brown. Q. catesbaei, myrtifolia, texana. 



23. Callirhytis ovata Weld, p. 222. 



Cells in thick brown bark, forming a smooth abrupt local swelling of a small area. 



of one to five square centimeters, number of cells evident from outside. Q, 



coccinea, rubra 24. Callirhytis rubida Weld, p. 224. 



Similar local swelling, number of cells not so apparent. Q. coccinea 



25. Callirhytis marginata Weld, p. 225. 



4. Detachable galls at crown (either on main stem or at base of sprouts from stumps 

 or on "runner oak" sprouts). 



Single or scattered in small numbers: 

 Monothalamous — 



Hemispherical, rugose to nearly smooth, 10-15 mm. in diameter, leaving a 



radiating scar when detached, woody when mature. Q. alba, macrocarpa, 



bicolor, prinus, stellata, chapmani 18. Callirhytis corallosa Weld, p. 216. 

 Fleshy, thin-walled, gray, densely short pubescent, spherical or with pointed 



apex. In spring. Q. chapmani, margaretta 12. Biorhiza ocala Weld, p. 207. 

 Small, pointed at apex, shell thin and brittle. Q.fendleri. Colorado. 



37. Weld No. 704, p. 242. 

 Spherical, 5 mm. in diameter, wall thin, surface brown and pubescent. On 



a deciduous oak at Las Vegas, New Mexico 40. Weld No. 708, p. 243. 



Hemispherical, 2-3 cm. in 'diameter, brown when mature, disintegrating in 



time leaving a rough cell on bark persisting for years. Q. vislizeni, cali- 



fornica, agrifolia See No. 22, p. 222. 



Oval, brown, on thick bark at crown. Q. catesbaei, texana, myrtifolia. 



See No. 2S, p. 222. 

 Onion-shaped, longitudinally striate, pointed at apex, reddish-brown to 



white. Q. rubra, velutina, marilandica, texana See No. 11, p. 206. 



Polythalamous — 



Large, rounded, brown, up to 9 cm. in diameter, when mature like rotten 



wood inside with many thin-walled brittle cells. Q. alba, macrocarpa, 



bicolor, prinus 19. Callirhytis maxima Weld, p. 217. 



Similar to above on Q. stellata Probably No. 19, p. 217. 



Smooth, brown, 15 mm. in diameter, spongy interior decays leaving a mass 



of loosely-connected ribbed woody cells. Q. rubra 36. Weld No. 405, p.242. 

 Hemispherical, dense tawny yellow tissue inside with a few cells at base. 



Q. chrysolepis See No. 26, p. 226. 



