ZETHUS. 



19 



to enable one to distinguish these exceptional species from the 

 Eumencs (viz. : the clypeus transverse and not longitudinal, the 

 mandibles truncate and not tapering, the head emarginate behind). 

 The petiole is, in general, less strongly punctured than the thorax, 

 more strongly than the abdomen. 



Among the species of this division the antennae of the males 

 are terminated, sometimes by a rolled-up spiral, sometimes by a 

 hook. They form, in this way, two parallel series, based upon 

 this character; in each one of them one sees the second abdominal 

 segment at one time subsessile and at another becoming more and 

 more pediculate. These two series continue in the Didymogastra. 

 The two forms of antennae combine with all the degrees of pro- 

 longation of the abdomen, thus showing that the character drawn 

 from the manner of termination of the antennas is not of any 

 generic value. 



As the most of the insects of this genus arc not well described 

 in my "Etudes sur la Famille des Vespides" I will here give a 

 diagnosis of the species of Meridional America which I have 

 before my eyes : — 



A. Aniennse of the males terminated by a rolling-up spiral. 



a. Petiole presenting a ?iodtdous or ovoid expansion. 



6. Z. arietis Fabk.— Niger, capite et thorace valde cribratis. Clypeus 

 cribratus, integer, apice subtruncatus. Pronotuin vis carinato-margi- 

 natum; inetauotum minus rugosuui, serieeum, in medio excavatum, 

 striatum. Petioli tumor hand nodosus, elongatus ut in Z. Westicoodi, 

 at angustior, nitidus, teuuiter punctatus ; abdominis 2m segmentum 

 paulum (sed distincte) petiolatum, elongatum, ovato-dilatatum (nou 

 globoso-dilatatum ut in Z. spinipede, Westicoodi, etc.). Petiolus et pedes 

 rufi; aloe iufuscatse eyaneae ; % anteunis subtus apicem versus fulvis. 

 Longit 0.017. 



Vespa arietis Fabr. Ent. Syst. II, 1793, 282.-Oliv. Encycl. Metli. Ins. 

 II, 676. 



Polices arietis Fabr. Syst. Piez. 2S0, 50. 



Zethus arietis Sauss. Vespides, I, 14, 11 ; Revue Zool. X, 1858, 64. 



Sab. Brazil. 



?. Z. rufinodiis Latr. 



Eumenes rujinoda Latr. Genera, IV, 1S09, 137, pi. xiv, fig. 5.— Sauss. 



Vespides, I, 42, 19, 

 Zethus rujinodus Sauss. Vespides, III, 118, 4, pi. vi, fig. 3, J . 



