NORTH AMERICAN HYMENOPTERA. 63 



My genus Dri/orhizo.renn,'^ and Befo)iocn.ema INIayr, are identical, 

 and were described about the same time. While there can be no (ques- 

 tion raised as to my having forwarded my descri|)tion for publication 

 first, yet from correspondence with Dr. Mayr I find he has jjriority 

 in pul)lication, and I have given his name the preference. 



Sub-tamily III. — Inc^uilin^. 



All the species in this group are termed guest fliies ; they are gal- 

 livorous and live in the galls made by species of the former sub- 

 family, from which they are hardly distinguishable. 



The much larger second abdominal segment and tlie almost always 

 closed radial area easily distinguish them. 



The species in our fauna represent but four genera separated as 

 follows : 



Synoptic Table of the Genera. 



A. — Radial area closed, scutellum bifoveate. 

 b. — Face coarsely striate. 



Thorax with distinct, almost parallel parapsidal grooves ; secoud abdominal 

 segment occupying nearly the whole surface of abdomen, divided appar- 

 ently by a very delicate, connate suture; ovipositor sheaths Y'ri>jecting 

 above upper surface of abdomen ; antennse in 9 1~' % In-jointcd. 



(2) C'froptres Hartig. 

 Thorax with parapsidal grooves converging behind ; second abdominal seg- 

 ment occupying the whole surface of abdomen : i)etiole striate, ovipositor 

 sheaths not projecting; antenna- in 9 1-1. % 15-jointed, second joint in % 



excised (.3) Syiiergiis Hartig. 



bb. — Face not coarsely striate. 



Thorax with parapsidal grooves delicate, converging behind ; second ab- 

 dominal segment in 9 occupying nearly the whole surface of abdomen, 

 in % subequal with third; ventral valve greatly projecting; ovipositor 

 sheaths projecting; antennte 9 l~t % 14-jointed. 



(1) Periclistiis Forster. 

 AA. — Radial area open, scutellum broad, not foveate. 



Thorax smooth, without parapsidal grooves ; secoud abdominal segment oc- 

 cupying the whole surface of abdomen ; ovipositor sheaths not projecting; 

 autennte with first joint very short, 9 13, % 14 -15-jointed. 



(4) iiiapliolytu!^ Forster. 



.Section II.— CRYPTOGAHTRI. 



Sub-family IV. — All( )TRri x.t:. 



In this grouji all the species are small, highly polished and closely 

 allied to the Iiuiuilime ; tliey are, however, easily distinguished from 

 that group by the subequal second and third abdominal segments 

 and by their very lonir subfiliform. moniliform antennae. 



