30 BULLETIN 45, UNITED STATES NATIONAL MUSEUM. 



This interesting observ^ation of Haliday's on the habits of a species 

 in this group is quoted at length as being quite unique and contrary 

 to the observations matle on the liabits of tlicse insects by all subse- 

 quent writers. It probably iiiHuenced Ualiday into placing the Ueth- 

 ylida^ among the Aculeata; but Ave can see from this observation that 

 they are not true Aculeata, for the insect observed by Ualiday would 

 unquestionably have stung the.larva into insensibility fas all Aculeata 

 do|, before attempting to carry it to its cell. 



The genera and species are numerous and are widely distributed, 

 being ftmiul in all i)arts of the world. 



It is believed that the following synoptic table, prepared with 

 great care, will enable the genera of this difficult group to be readily 

 determined by the student without recourse to the full generic de- 

 scription : 



TABLE or (lENEKA. 



I'KMAI.KS. 



Wiuged 3 



Wingless. 

 With ocelli 2 



Without ocelli ; antcniiin 13-joiiite«l. 



Metathorax much contracted or straiigiilatcMl at hase. 

 Scutellnm present. 



Maxillary palpi 6-joiiite<l; niiiudililes ,'{- or l-deutato.. .Pristocera King 

 Scutellnm wanting. 



Maxillary palpi 0-jointed; nnindiijlcs li-dentate Isohracuii'm Forster 



Metathorax not much contracted .it base, <iuadrate. 

 Scutellnm present. 

 Maxillary palpi 5-jointed; niandihlcs Ith'ntate ... ..Sclkrokerma Lati. 

 Maxillary palpi t-jointcd; mandihli'.s 3-dentate, 



DiMsoMrnAi.L's Ashni. gen. nov. 

 Maxillary palpi 4-jointed; normal; mandihlts 2-dentate. 



Labial palpi 3-jointod Ateleoptert's Forster 



Maxillary palpi 4-jointed, deformed; mandibles 2-dentate. 

 Labial i)alpi 3-jointiMl Apenesia Westw. 



2. Antennie 12-jointed; maxillary palpi 4-jointed Cepiialonomia Westw. 



3. Anterior wings with a stigmated marginal vein and a marginal cell, the radius 



always well developed 4 



Anterior wings without stigmated marginal vein and margiaul cell, the radius 

 not, or but slightly, develoited. > 



Anterior wings without marginal and stiginal vein. 



AntenniB 12-jointed ; no basal cell Cephalonomia Westw. 



Antennie 13-jointed ; one basal cell Ateleopterus Forster 



Anterior wings Avith a short linear marginal vein and a short radius. 

 Two hasal cells about equal in length. 



Antenna? 13-jointed L.elics Ashni. gen. nov. 



Antenna^ 12-jointed Bkthvus Latr. 



4. Basal nervure with a branch directed backwards, sometimes forming a small 



cell ; a parastigma 6 



Basal nervure without a branch directed backwards; no parastigma. 

 Anterior wings with an incomplete marginal cell 5 



