112 BULLETIN 85, UNITED STATES NATIONAL MUSEUM. 



tliat these gall variations have no specific significance. He describes 

 a wide range in form variation from the typical perpendicular, 

 mammiform gall to a short, rounded gall without the nipple, or 

 even concave at the end. He further states that a great many of 

 these different galls were placed singly in pill boxes and the adults 

 bred out. With a few possible exceptions, all the adults thus 

 bred out were typical c.-mamma. A few he thought might be 

 varietal forms. He concludes, and correctly I believe, that gall 

 variations such as are described above have little or no specific 

 significance. These several species listed above are therefore either 

 identical with c.-mammna or are varietal forms of it. 



PACHYPSYLLA C.-VESICULUM Riley. 



Figs. &3, 241, 292, 454. 



Pachypsylla celtidis-vesiculum Riley '83b: '90:618.— Beutenmuller '92:275; 

 '04:35.— Jarvis '06: 65.— Stebbins '10:33. 



Very close to c.-mamma, differing as follows : Much smaller, about 

 2 mm. long to tip of folded wings, rarely over 2.5 mm., less robust; 

 similar in general coloration except genal cones distinctly lighter 

 than vertex; head usually less perpendicular. Genitalia relatively 

 smaller. Wing venation not exactly similar (see figure). Galls 

 distinctly different, blister-like and similar on both sides of leaf, 

 never mammiform or elongate; often scarcely raised above surface 

 of leaf. 



Described from many males and females from Ames, Iowa (Mally), 

 and from Ithaca, New York (Crawford), bred from Celtis galls, 

 October, 1912. 



PACHYPSYLLA C.-GEMMA Riley. 



Figs. 67, 243, 453. 

 Pachypsylla celHdis-gemma 'Rii.EY '88:74.— Beutenmuller '92:275. — Mallt '93:138. 



Length of body 3.2 mm.; length of forewing 3.3; width of head 1.2. 

 General color yellowish brown, variable in shade; head and thorax 

 dirty yellow with a tinge of brown. Body moderately large, robust, 

 surface glossy, not pubescent. 



Head almost vertical, much narrower than thorax; vertex large, 

 straight on posterior margin, not converging toward front, not 

 pubescent as in preceding species, with a shallow fovea on each side 

 of median line, punctate; genal cones small, short, rounded apically, 

 projecting outward and slightly forward from plane of vertex, 

 sharply depressed and separated therefrom, divergent, pubescent. 

 Antennae very short, scarcely as long as width of head. 



Thorax very large, massive, strongly arched, glabrous and very 

 finely punctate. Pronotum not very long, almost vertical, lateral 

 margin straight. Wings broad, large, rather rhomboidal, light 

 brown throughout, coriaceous, about twice as long as broad, sides 



