NO.120G. ICHNEUMON FLTES—ASHMEAD. 67 



Transverse median nervure in front wings originating usually before the basal 

 nervure, rarely interstitial or slightly beyond it; antennn; and tarsi 

 ringed with white; mesonotuni, scutellnin, niesopleura, and hind 

 coxa3 always alutaceous (•153) Euryjrroduti I lolnigren. 



Tribe II. CTENISCINI. 



1855. Ti'ypJionideH homalopi Holmgkex (part), Svensk. Yet.-Akad. Handl., I, 



p. 98. 

 1868. Exenterokhv FiiRfiTER, Yerh. d. natiirh. Yer. pr. Rhcinl., XXY, pp. 144 and 



194. 

 1883. Ctenisdna, Tribus, Thomson, Opus. Ent, IX, pp. 875-880. 

 1894. Exenterini, Tribe II, Ashmead, Proc. Ent. Soc. Wash., Ill, p. 277. 

 1897. Exenterini, Tribe, Davis, Trans. Am. Ent. Soc, XXI Y, p. 227. 

 1900. Cteniscini, Tribe II, Asitmead, Smith's Insects of New Jersey, p. 577. 



This tribe is readih" distinguished l)y the posterior tibi.e, except in a 

 single case, helng entirely vyithout <ipical sjmrs. Five tribes only have 

 the posterior tibi{« armed with a single apical spur, naniel}^ the 

 Orthocentrini., the Exochinl^ the Tylecomnini., the Sphincthi/, and the 

 MetopUni^ the others having two apical spurs. Of those just men- 

 tioned, having but a single apical spur to the hind tibiic, all, except 

 the Metopiuii^ have, however, tioo apical spurs on the tiiiddle tibia% 

 whereas the Cteniscini and the Metopllni have but one. The wonder- 

 ful peculiarities of the face and scutelluni in this last group, brought 

 out in my table, will, however, enable a novice to distinguish it. 



Twelve genera have been characterized in this group, distinguish- 

 able as follows: 



TABLE OP GENERA. 



Teeth of mandibles of an equal length 2 



Teeth of mandibles of an unequal length. 



Clypeus anteriorly broadly truncate; claws at base very feebly pectinate or 



simple ( 454 ) Acrotom us Forster = Delotomus Holmgren. 



Clypeus anteriorly broadly rounded; claws strongly pectinate to beyond the 

 middle ("155) Anisoctenion F<)rster. 



2. Claws not pectinate 8 



Claws pectinate. 



Lateral marghis of first abdominal segment normal 3 



Lateral margins of first abdominal segment thrice emarginate. 



(456) Tricamjilas Fdrster. 



3. Front wings vitJb an areolet 4 



Front wings ivithout an areolet (457 ) EridoUus Fiirster. 



4. Hind ti))ipe vith a single small apical spur. 



(458) Microplectron Forster ^= tSmkropledrus Thomson. 



Hind tih'ix 7ri(hout an apical spur, the apex crowned with several minute spines. 



Abdomen liroadly sessile, the first segment strongly widened quite to the 



base, scarcely distinguishably wider at apex 5 



Abdomen almost petiolate, the first segment distinctly narrowed toward 

 base (459) Cteniscns Haliday = Exenterus Hartig. 



5. Metanotum with the areola sharply circumscribed and wider than long 6 



Metanotum with the areola not sharply circumscribed and wider than long. 



(460) Picroscopus Forster. 



