NORTH AMERICAN HYMENOPTERA. 63 



and all of the male sex. The females seemed to have made their 

 way out. On comparing them with the njales of R. radicum I found 

 them to agree so closely that I was disposed to look upon them as 

 merely a variety of that species. Further study revealed some 

 minor differences, and at least one characteristic that seemed to 

 entitle them to rank as a distinct species. 



The differences noted are as follows: the first joints of the an- 

 tennfB are not as dark reddish brown as in R. radicum, the antenna? 

 are not as long, the mesothorax is shining punctate, the punctuation 

 much finer, the feet are not as dark, and, while the wings are possibly 

 a shade deeper yellow, the clouded spots seen on the wings of R. 

 Tadicmn are wanting, and the enlargement of the second transverse 

 vein at the base of the radial area in that species is wanting in this. 

 But the most notable difference is, that while the parapsidal grooves 

 in R. radicum almost touch each other at the posterior margin of 

 the mesothorax, they are so widely apart in this species that the 

 difference cannot escape notice. 



There are species in this genus that resemble each other more 

 nearly than these two, but in such cases the galls are very distinct. 

 If further observations show it to be only a variety it is sufficiently 

 marked to deserve a name. 



5. R. iiebiilosus n. sp. 



Round, hollow, thin shelled, monothalamous galls thi-ee-sixteenths 

 of an inch, or less, in diameter, on the underside of the leaves of the 

 wild rose {Rosa blanda and probably R. Carolina). They are usually 

 situated on the lateral veins on the lower half of the leaf and close 

 to the mid-vein. The surface in the green galls is quite smooth, but 

 when dry it is slightly rough and uneven, but not pubescent. There 

 is no larval cell. 



These galls are often parasitized, and such are sometimes quite 

 solid and contain several larval chambei'S. The same often occurs 

 in galls of R. hicolor. I have received this species from correspon- 

 dents in widely separated sections, but in most cases the galls were 

 immature when collected and produced nothing, and 1 have only 

 one gall-fly, a male, of this species. 



Gall-flies. — Head black, very broad, front from the eyes and iticluding the 

 base of the antenuse, perfectly flat; ocelli prominent, and included in a smooth, 

 shining space bounded by a distinctly impressed line, outside of this space the 

 vertex is hairy and finely reticulated ; antennpe 14-jointed; joints one and two 

 deep brownish yellow, remaining joints black, third twice as long as the first 



