128 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



18. Mesonotum with lateral lobes black, spotted with ferruginous; 



first abdominal segment black at base, ferruginous at apex; 

 sides of ocellar basin distinctly raised; frontal crest prom- 

 inent and unbroken; median fovea broad, shallow, not dis- 

 tinctly defined; saw-guides rather broad, slightly excavated 

 above, pointed, and with rather dense whitish hairs at tip; 

 body black, with tip of clypeus, labrum, posterior orbits, 

 angles of pronotum, tegulse, spot on the lateral lobes of meso- 

 notum, abdomen beyond the middle of the first segment, and 

 legs except the bases of the coxae and the hind tibiae and 



tarsi, yellowish ferruginous. Length 7 mm populi 



Mesonotum with the lateral lobes entirely and the entire first 

 abdominal segment ferruginous; ocellar basin distinctly de- 

 fined ; frontal crest very prominent, unbroken ; median fovea 

 distinctly excavated, triangular; saw-guides narrow and taper- 

 ing ; body black, with clypeus and labrum pale ; angles of pro- 

 notum, tegulae, lateral lobes of mesonotum, abdomen except 

 the basal plates and saw-guides, and legs except hind tibiae and 

 tarsi, j^ellowish ferruginous. Length 10 mm hudsonii 



19. Hind femora mostly black; ocellar basin distinct, with sharply 



raised sides; frontal crest broad, rounded, unbroken; me- 

 dian fovea deep, circular; saw-guides strongly tapering 

 toward the rounded apex, nearly straight on upper margins, 

 with very short, inconspicuous pubescence; body yellow- 

 ish or ferruginous, with base of antennae, spot about ocelli, 

 occiput, pronotum except outer angles, spot on lobes of 

 mesonotum, spot about the cenchri, basal plates, and first ab- 

 dominal segment at base, black ; pectus, hind femora except 

 at base, tips of hind tibiae, and hind tarsi, blackish brown. 



Length 6 mm antennata 



Hind femora entirely pale; ocellar basin with poorly defined 

 walls; frontal crest entire or indistinctly broken; median 

 fovea rather deep at apex, oval; saw-guides rather narrow, 

 rounded at extremity, with short hairs ; body luteous or ferru- 

 ginous, with head below antennae, except the supraclypeal 

 area, orbits, more or less of antennae above, large spot on 

 middle of lobes of mesonotum, scutellum more or less, 

 lower part of pleurae, pectus, apices of posterior tibiae, 

 and posterior tarsi, brownish black. Length 7-7-5 nim. 



ribesi 



20. Head with the orbits not pale 21 



Head with orbits pale 23 



21. Mesonotum black ; ocellar basin distinctly defined, with prom- 



inent walls; frontal crest strongly bent anteriorly, 

 scarcely broken centrally; median fovea triangular, deep, 

 with sharp limiting ridges; sawi-guides short, rounded 



