376 VESPIDyi:. 



Key to the Genera. 



A. First abdominal segment narrowed into a 



petiole. 



a. Fore wing with 3 or 4 cubital cells. 



a'. Petiole much longer than the rest of 

 the abdomen. 

 a'-. Mandibles and clypens long beak- 

 shaped, the former not dentate . . Ischnogaster, p. 376. 

 b^. Mandibles and clypeus short, the 

 former with teeth at apex, the 



latter pentagonal Belonogaster, p. 381. 



b'. Petiole shorter than or equal in length 

 to the rest of the abdomen. 

 a^. Median segment not steeply sloped, 

 compressed towards the apex ; man- 

 dibles with four teeth, all nearly 



equal in size Polybia, p. 382. 



i*. Median segment somewhat steeply 

 sloped, not compressed towards the 

 apex ; mandibles with four teeth at 

 apex, the inmost one smaller than 

 the rest, acute Icaria, p. 385. 



b. Fore wing with only two cubital cells . . Paraicaria, p. 392. 



B. First abdominal segment not narrowed into 



a petiole, pseudosessile. 



a. Median segment always transversely 



striate ; 1st abdominal segment fusi- 

 form towards the base Polistes, p. 393. 



b. Median segment never transversely striate ; 



1st abdominal segment steep or roundly 



truncate at base Vespa, p. 399. 



Genus ISCHNOGASTER. 

 Ischnogaster, Gu^r. Voy. Coq., Zool. u, pt. 2, p. 269 (1838). 



Type, /. fuJffijyennis, Guer. 



Range. Neotropical, Oriental, and Australian regions.' 



Head flat ; eyes large, very prominent, the inner orbits on their 



upper halt' with a sinus, the sinus small and narrowed in the 



larger, deeper and broader in the smaller species ; mandibles longand 



pointed, simple, without teeth, 

 nearly always covered by the long 

 acutely pointed clypeus ; an- 

 tennae subclavate, the apical joint 

 ( 5 ) acutely conical, in the male 

 forming a very small crotchet 

 or hook applied closely against 

 the 12th joint, their insertion 

 high up just on a level, or a little 

 below the sinus of the eyes. 

 Thorax very short, globular, pro- 

 rhorax truncate anteriorly, not 



'F\g.\\2.~hchnogastermicanii,2. \. prolonged into a collar or neck; 



scutellum, postscutellum, and 



median segment forming a rounded, very steep, nearly vertical slope ; 



