No. 22.] HYMENOPTERA OF CONNECTICUT. Ill 



femora white; third and fourth segments of the antennae 

 subequal ; pentagonal area distinct, the 'frontal crest slightly- 

 broken, the median fovea small, circular ; basal two-thirds of the 

 wings dark, smoky black. Length 6 mm. Larva feeds on 

 Populus tremuloides. 



Nematin^.* 



The types of the following species are not accessible and it 

 is impossible to locate them in the tables. 



Nematus (Pteronus?) longicornus Say. 



Body black, with the postgense, orbits, face below the anten- 

 nae, the tegulae, the angles of the pronotum, the pleurae except 

 two black spots, the body beneath, and the legs (except the api- 

 cal half of the hind femora, their tibiae, and their tarsi), whitish; 

 antennal segments three and four subequal ; clypeus angulately 

 emarginate ; male with the antennae pale fulvous beneath ; the 

 third segment shorter than the fourth and curved at base. 

 Length 12 mm. 



Connecticut (E. N.). 



*Nematus (Pachynematus) nigritus Norton. 



Body black, with the postgenae, the clypeus, the labrum, the 

 tegulae, and the apex of the abdomen above and below, yellowish ; 

 the trochanters, the apical half of the femora, the tibiae except 

 the tips and base of the hind pair, reddish white; antennae with 

 the third segment shorter than the fourth ; clypeus hardly 

 emarginate. Length 12 mm. 



Connecticut (E. N.). 



Key to Genera. 



1. Claws simple, without a tooth ; clypeus emarginate ; head 



with frontal area indistinct or wanting Diphadnus p. 112 



Claws with a tooth 2 



2. Claws with a small, erect tooth at middle 3 



Claws cleft at apex, the two rays usually subequal in length. . 5 



3. Clypeus emarginate, sometimes very slightly; vertex with 



a fairly distinct frontal area; radio-medial cross-vein 

 always present Pachynematus p. 1 15 



•In the preparation of the tables dealing with this subfamily free use has been made 

 of a paper by C. L. Marlatt, "Revision of the Nematinae of North America," Bull. No. 3, 

 Technical Series, Bureau of Entomology, U. S. Dept. of Agriculture. 



