NORTH AMERICAN HYMENOPTERA. 67 



The fully grown gulls are round and measure three-eighths of an 

 inch in diameter, and each has a short, blunt spur at the apex pre- 

 cisely like that of H. duricorid Bass., and they might easily be taken 

 for dwarf specimens of that species, though the surface is more hoary. 

 The larval cell is, in these specimens, attached to the gall, hut can 

 be detached without breaking. The body of the gall is hard, and 

 around the cell tliere is a thin even layer of rusty brown, and out- 

 side this a light gray color prevails. 



Opening three of the galls I found in each a full grown female 

 gall fly that had failed to make its way through the hard wall en- 

 closing it. 



The description of i/. coral/ inus, ^ust given, ai)plies to this species, 

 • except as follows : 



The thorax and legs are somewhat darker and less hirsute, and the latter are 

 of a clear, shining, almost resinous aj.pearance. The abdomen is black aad 

 shining, with a tinge of brown, and the hairiness is confined to the sides of the 

 second, third and fourth segments, and is so very sparse, short and fine, as to 

 escape observation unless highly magnified, while the hirsuteness of H. corallinus 

 gives it a hoary appearance even to the naked eye. The parallel lines on the 

 mesothorax are more widely separated, and these with the line over the base of 

 each wing are darker, broader and more shining, and, by contrast with the gen- 

 eral surface, appear black. The parapsidal grooves, inconspicuous in H. corallinus 

 are still more so in this and would easily escape notice. The wings difl'er mainly 

 in the radial area, which is much larger in this species. Length : body, .15 inch. : 

 wings. .20 inch.; antennse, .13 inch. 



4. H. Sileri n. sp. 



Galls ovate from a broad base, sessile on the twigs of an oak 

 growing in southern Utah, .sometimes elongated at the i)oint but not 

 beaked, shining brown, yet not quite smooth. Many specimens are 

 deeply and irregularly cracked, and from some the epidermis has 

 flaked off". They rarely exceed one-fourth of an inch in diameter, 

 and many are a little less than that. Internally they are harder 

 than H. duricoria, H. globulus and H. rugosus, which they resemble, 

 except that they are smaller. The larval cell is closely imbeded, 

 but .separable from the gall. 



I have reared no gall-flies from these, but have found, on cutting 

 some of them open, several apparently mature female specimens. 



Gall-flies. — Dull dusky, reddish brown, except the abdomen, which is black 

 and shining. Anteunx 14-jointed, first short, second very small, third and fourth 

 moderately long and equal, the remaining gradually shorter, except the last, 

 which is one-third longer than the preceding. Entire thorax moderately hairy, 

 parapsidal grooves from the scutellum half way to the collare diverging ; parallel 

 lines from collare a little more than halfway to the scutellum distinct and sm(K;th 



