THE CANADIAN ENTOMOLOGIST. 103 



Clypeus anteriorly subtriangularly emarginate or tridentate ; 

 maxillary palpi 6 jointed, the first joint short, the following 

 joints longer, subequal ; labial palpi 4-jointed, the first joint 

 shorter than the 2nd and 3rd united ; abdomen spotted. 



(South America) Spilothynnus, Ashm., gen. nov. 



(Type Thynnus laetus, Klug.) 



27. Clypeus anteriorly subemarginate, deeply emarginate or 



tridentate 28. 



Clypeus anteriorly rounded, not emarginate. 



Abdomen fusiform, a little longer than the head and thorax 

 united, maculate or fasciate ; maxillary palpi 6-jointed, the 

 last three joints much longer than the first three, or twice as 

 long; labial palpi 4-jointed, joints i and 4 longer and slenderer 

 than 2 and 3, which are short, stout. (South 



America x^nodontyra, Westwood.) 



(Type A. tricolor, Westw.) 



28. Clypeus anteriorly subemarginate; maxillary palpi 6-jointed, joints 1-3 



rather short, joints 4-6 long, subequal, five or six times longer than 



thick ; labial palpi 4-jointed, the first joint long and slender, about 



as long as 2-4 united ; abdomen fasciate. (South America.) 



Clypeus anteriorly bidentate ; maxillary palpi 6-jointed, the joints 



obconical, unequal, the first four short, the third and fourth much 



longer than the second. (South America) Ornepetes, Gue'rin. 



(Type O. nigriceps, Gue'r.) 



29. Pygidium not very narrow, oblong, rounded at apex, usually shagreened, 



punctate, rugulose or striate; if smooth, which is rare, it is curiously 

 modified, compressed towards base and broadened into an elevation 

 posteriorly ; basal segment of abdomen ivithout a strongly curved 

 furrow on each side or a strong transverse furrow before the apex.. 30. 

 Pygidium very narrow, smooth and shining; basal abdominal segment 

 tvith a strongly curved furrow on each side, or a deep, transverse 

 furrow before apex. 



Basal abdominal segment with a strongly curved furrow on each 

 side ; second segment with about three transverse folds or 

 carinse ; pygidium with two pencils of long golden hairs that 

 curve and meet above the narrow elevation on 



its disk Thynnus, Fabricius. 



Basal abdominal segment with a strong transverse furrow just 

 before apex ; second segment with three transverse folds or 



