30 BULLETIN 45, UNITED STATES NATIONAL MUSEUM. 



This interestiug observation of lliiliday's oii the habits of a species 

 in this group is quoted at leni^th as being quite unique and contrary 

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

 quent writers. It probably intiuenced Haliday into placing the Beth- 

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

 they are not true Aculeata, for tlie insect observed by Haliday would 

 unquestionably have stuug the larva into insensibility [as all Aculeata 

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



The genera and sjtecies are numerous and are widely <listributed, 

 being found in all parts 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 OF (lENEKA. 



I'KMAl.KS. 



Wiugeil 3 



AVingless. 



With ocelli 2 



Without ocelli; antcuu.'D IS-joiiited. 



Metathorax much contractetl or stniuyulated at base. 

 Scutcllum present. 



Maxillary palpi 6-joiiited; iiiamliblcs ;^- or 4-deutate.. .Pristocera Klug 

 Sciitelluui Avantiug. 



Maxillary ])ali)i (5-j<iiiited; mandildes 3-deutate Isohraciiium Eorster 



Metathorax not much contracted at liase, (luadrate. 

 Scutellum present. 



Maxillary paljti 5-jointed; mandihhis 4-dcntate Sclkrodkr.ma Latr. 



Maxillary palpi 4-jointcd; mandibles 3-deutate, 



I)i8S()MPn.\LUS Ashni. gen. nov. 

 Maxillary palpi 4-jointcd ; nonnal; mandililcs 2-deutate. 



Labial palpi 3-jointcd ArELEOPTERrs Eorster 



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

 Labial palpi 3-jointcd Apjcnesia Westw. 



2. Antenna) 12-jointed; maxillary palpi 4-jointed Cephaloxomia Westw. 



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



always well developed 4 



Anterior wings witliont stigmated marginal vein and marginal cell, the radius 

 not, or but slightly, develojxd. 

 Anterior wings without marginal and stiguial vein. 



Antennic 12-joiuted; no basal cell Cephalonomia Westw. 



Antenme 13-jointed ; one basal cell Ateleopterus Eorster 



Anterior Avings with a short linear marginal vein and a short radius. 

 Two basal cells about equal in length. 



Antenna', 13-jointed L.elius Ashm. gen. nov. 



AntenniB 12-jointed BETUYi.rs Latr. 



4. Basal uervure 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 



