176 THE CANADIAN ENTOMOLOGIST. 



A spot on each side of segments 2, 3 and 5 (i) sexnotatus. 



A spot on each side of segments 2-3 (11) quadrisignattis. 



Males. 



Intermediate joints of antennae not longer than wide ; tegulse, knees 

 and apex of tibise usually yellow; scutel black or marked with yellow, 

 sometimes red ; abdomen varying from 6-banded to 4-spotted . <7z/«/?/.y. 



Intermediate joints longer than wide ; tegulae and legs red ; scutel 

 usually red; abdomen varying from 6-banded to 'i-?,\>Q)\.\.td,.ciineatus. 



Cephen, gn. nov. (Type JVanada Texana, Cresson). 



Female. 

 Black ; labrum, joints 1-3 and legs red ; lemon-yellow ornaments as 

 follows : Base of mandibles, sides of face, line behind summit of 

 eye, collar, tubercles, subarcuate mark on pleura, two spots on scutel, 

 postscutel, spots on middle and hind coxae and on apex of hind tibiae, 

 narrow fasciae on segments 1-5 above and arcuate marks on sides of 



3-4 beneath Texanus. 



Male. 

 Like the female ; face, clypeus, spot above, and labrum 



lemon-yellow Texamis. 



Centrias, gn. nov. (Type Nomada erigero7iis, Rob.). 



Females. 



Insect red ; sutures, depressed and concealead portions 



more or less black , Americanus. 



Insect black ; mandibles, face, joints 1-3, tubercles, tegulse, line above, 

 patches on pleura, scutel, legs, and sometimes venter, red ; malar 

 space, collar, axillre, postscutel and abdominal fasciae, yellow ; the 

 latter interrupted on 1-3, continuous and paler on 4-5 ; abdomen 

 coarsely punctured, margins of segments reflexed, beneath the punc- 

 tures are coarse, strong and dense erigero7iis. 



Males. 



Hind femur arcuate ; antenna with a pale annulus ; abdomen red at 

 base, black beyond, yellow fascire interrupted on segments 1-2, con- 

 tinuous on 3-6 ; 7 strongly notched ■.Americanus. 



Hind femur simple ; antenna without a pale annulus ; abdomen black, 

 yellow fascite interrupted on segment i, continuous on 2-6, 7 slightly 

 notched ; other ornaments like the female, but the mandibles, face, 

 scape in front, flagellum at base beneath, tubercles, tegulse, spot on 



