168 CHARLES ROBERTSON. 



1. Body short, robust ; abdomen cordate, broad and slightly convex above; seg- 



ments 2-3 of about equal width, 4 narrower; 6 much longer than 5, 

 straight or slightly concave and lipped in profile; claws with an acute 



basal tooth 4. 



Body long, slender; abdomen oblong, more cylindrical ; segments 2-4 of about 

 equal width ; 6 in profile convex to base of distinct lip; scopa whitish, 

 black on segment 6 2. 



2. Joint 3 of maxillary palpi hardly pubescent, shorter than 1 -4- 2 ; claws with 



sharp basal teeth ; segments 2-4 without whitish pubescent fascise in 

 basal grooves; 6 longer than 5; joint 1 of labial palpi shorter than 2; 

 third tooth of mandibles subquadrate, truncate, beveled. ..C'eratias. 

 Joint 3 of maxillary palpi strongly pubescent, longer than 1 -f- 2; claws with 

 blunt basal teeth ; segments 2-4 with whitish pubescent facia? in basal 

 grooves; 6 hardly longer than 5, much higher than long, abruptly de- 

 clining to short lip ; labial palpi with joint 1 longer than 2; third tooth 

 of mandibles acute ; middle teeth farthest apart 3. 



3. Clypeus truncate or slightly tuberculate ; joint 1 of labial palpi one-fifth longer 



than 2 ; length 8-11 mm. Oligotropu*. 



Clypeus strongly 6-dentate; joint 1 of labial palpi one-fourth longer than 2; 

 length 13-14 mm Gnaf liodon. 



4. Mandibles 4-dentate Mega«'liile. 



Mandibles 5-dentate ; scopa yellow ; disc of segment 6 with long erect hairs; 



joint 1 of labial palpi a little shorter than 2 5. 



5. Hairs on segment 6 yellowish ; length 13-15 mm Yaul Iion;i rtis 



Hairs on segment 6 black ; length 11 mm A ill lieinois. 



Males. 



Mandibles without a great tooth below; segment 6 with a low carina, emarginate 

 in the middle, apical margin with 4 blunt teeth ; 3 ventral segments; 

 cheeks distinctly punctured ; front and middle tibiae and front tarsi 

 red anteriorly; front tarsi simple; mesonotum in front bilineate with 

 white pubescence t'lielostoiiioides. 



Mandibles with a great tooth below 1. 



1. Front tarsi simple, not flattened, black, or nearly ; 4 ventral segments 5. 



Front tarsi flattened 2. 



2. Coxal spines nearly obsolete; 3 ventral segments; joint 13 of antenna simple ; 



front tarsi black, joints 1-3 flattened, 4 simple but wider than long; 

 inferior manibular tooth a little before the middle; segment 6 with 

 two compressed teeth ; apical margin with two teeth on each side, the 

 lateral ones stronger ; 7 not produced ; cheeks with long white hair; 

 pubescent fascife on apical margins and basal grooves, more dense in 



the latter Oligotropus. 



Coxal spines distinct ; joint 13 of antenna broad and flat; front tarsi colored. ..3. 



3. Anterior coxae bare in front and with one or more bristles; front tarsi whit- 



ish, joint 1 with a boat-shaped scale; lower angle of cheek grooved, 

 with a posterior spine; segment 9 with carina ordinary, apical margin 

 with a carina on each side, but no spines; 7 pointed ; ventral segments 

 4 ; claws cleft and with an acute basal tooth C'eratiaM. 



