374 [May 



as long as the fourth, and I infer from this that the % of S. oneratus 

 which I do not possess, has, like the 9 > the third and fourth joints of 

 nearly the same length ; 3d, by the mesonotum always having more or 

 less yellow on the sides, whereas in S. lignicola it is altogether black, 

 the yellow being strictly confined to the collare ; 4th, by the black spot 

 on the upper part of the abdomen having a more definite, oblong out- 

 line, the tip of the abdomen (or rather of its second segment) and its 

 sides remaining yellow, whereas the limits of the black color in S. lig- 

 nicola are less well defined ; this color extends in the latter to the very 

 tip of the second segment and merges into brownish or brownish-yellow 

 on the sides; in many 9 specimens the venter and the ventral valve 

 are again blackish; 5th, the ventral valve of S. oneratus is shorter and 

 truncate at the tip; that of S. lignicola ends at an angle of about 

 45°. 



I possess five 9 specimens of this species, obtained from the galls of 

 C q. globulus Fitch (on Quercus alba), from a similar gall on Q. ob- 

 tusiloba and from that of C strobilana 0. S. 



2. Synergus lignicola 0. S. 



Syn. S. lignicola 0. S., Proc. Ent. Soc. Phil. I, p. 252. 



S. rhoditiformis Walsh, Proc. Ent. Soc. Phil. II, p. 499. 



The synonymy is admitted by Mr. Walsh himself, to whom I have 

 communicated specimens of my S. lignicola. My description was 

 drawn from rather pale specimens, and has to be corrected in the fol- 

 lowing points : 1st. The collare has a brown or black spot in the mid- 

 dle, which is more or less extended, being sometimes confined to a 

 narrow brown line, in front of the angle formed by the mesonotum an- 

 teriorly and sometimes extended into a large black spot, which crosses 

 over to the occiput, and occupies a small portion of it round the neck ; 

 the specimens bred by Mr. Walsh from the gall of 0. q. podagrse (Q. 

 tinctoria), and described as S. rhoditiformis. seem to have had this spot, 

 usually, of a large size. 2d. The pectus is black and the middle cox:t 

 not inserted on yellow ground as stated by me. The question of the 

 presence or absence of "two slight subdivisions" of the last joint of 

 the 9 antennae is unimportant, as it depends on the strength of the lens 

 used and on that of the eyesight. I perceive it in S. lignicola, as well 

 as in the specimens of S. rhoditiformis, which I owe to the kindness 

 of Mr. Walsh. His description being more detailed and accurate than 

 mine, will have to be relied upon for determining the species, keeping, 

 however, in view the remark about the collare, given above, and the cir- 

 cumstance that the ventral valve is not always of " a highly polished 

 black." but sometimes paler. As Mr. Walsh's specimens, reared from 



