ART. 19. GALLFLIES OF THE FAMILY CYNLPIDAE WELD, 3 



3. Galls Inside the acorn. 



A. Cells in a cluster, confluent or producing a stony mass more or less 



filling the interior and may be lifted out intact (pi. 2, figs. 4, 5, 6; 

 pi. 3, fig. 9). 



On Q. marilandlca Callirhytis fruticola A.shmead, p. 17. 



On Q. rubra, coccinea, texana. 



Callirhytis fructuosa, new species, p. 14. 



On Q. hrevifolia Callirhytis petrosa, new species, p. 13. 



On Q. affvifolia, icisHzenii, californiaa. 



Callirhytis milleri, new species, p. 11. 



On Q. hicolor Callirhytis lapillula, new species, p. 18. 



On Q. hypoleuca Callirhytis petrina, new species, p. 13. 



B. Cells single, not confluent, not separable from the wall of the acorn 



(pi. 8, fig. 10). 



On Q. agrifolia, loislizcnii, californica. 



Biorhiza eldoradensis (Beuteiunueller) , p. 5. 



The flies reared from these American acorn galls belong to but 

 four genera of Cynipidae. For the purpo^'es of the present paper 

 they may be separated as follows: 



KEY TO THE AMERICAN GENERA OF CYNIPIDAE PRODUCING GALLS ON ACORNS. 



1. Large black species. Thorax robust, v.ider than head, coarsely sculptured. 



Claws with tooth. Front wing smoky or clouded, margin ciliate. 



Amphibolips Reinliard, p. o. 



Not large black coarsely sculptured species. Thorax not distinctly wider 



than head. Front wing not clouded 2. 



2. Mesoscutum shining, smooth or very feebly coriaceous, claws simple. 



Biorhiza Westwood, p. 5. 

 Mesoscutum dull if coriaceous but usually sculptured 3. 



3. Tarsal claws simple. Front wing margin not ciliate. 



Callirhytis Foerster, p. 7. 

 Tarsal claws with tooth. Wing margin ciliate Andricus Hnrtig, p. 2Q. 



Genus AMPHIBOLIPS Reinhard. 



Of the eight described American species of Cynipidae producing 

 galls on acorns three belong to the genus Amphibolips. Their galls 

 are all of the same general type and are popularly known as " plum " 

 galls. They are relatively large, heavy, smooth, globular galls at- 

 tached by a single point to the side of the acorn cup and dropping to 

 tlie ground in late summer and autumn. They are borne on acorns 

 of the current season's crop and may or may not stunt them. When 

 fresh they are reddish l)rown, mottled, fleshy, with a larval cavity 

 in the center, the wall thick, dense, and often with a reddish juice. 

 After they drop they lose weight and may or may not shrivel, 

 wrinkle, and change shape somewhat; the kinds which wrinkle be- 

 come very hard. The flies of these three acorn-gall-producing species 

 belong in that section of the genus with clouded wings and are dis- 



