ZETIIUS. 45 



Division DIDYMOGASTRA Perty. 

 (Sauss. Vespides, I, 18 ; III, 120.) 



Second segment of the abdomen lengthened pediculate ; its 

 pedicular part forming at least a fourth of the length of the seg- 

 ment. The other characters as in Zethusculus. 



These insects have very slender forms on account of the extra- 

 ordinary length of their abdomen, by the double articulation of 

 which, they enjoy the singular faculty of folding the abdomen 

 beneath the thorax, and of placing the terminal pear against the 

 face of the head. 



The Didymogastra inhabit the hot regions of America. 



One cannot establish any line of demarcation between the 

 Zethusculus and the Didymogastra ; these last form the continua- 

 tion of the same genera and only represent the more lengthened 

 modification of the type. The two series, based on the form of 

 the antennas of the males, continue themselves in the Didymo- 

 gastra. So this division is wholly empirical, and should not be 

 preserved except to facilitate the determination of species. 



A. Antennas of the males terminated by a rolled spiral. 



39. Z. Poeyi Sauss. (Fig. 4, 4a.) — Niger, rugose punctatus, metanoto 

 vix striato, velutino ; petiolo polito, tenuiter pnnctato, gibboso ; secundo 

 abd. segmento laevi, nitido, pedunculo mediocriter elongato ; mandibulis, 

 frontis fascia, orbitis bis interruptis, pronotoantice,maculis2subalaribus, 

 tegulis, scutello et post-scutello antice, maeulis 2 metanoti, petioli apice 

 pedibusque, aurantiacis; his rufo vel nigro variis ; abdomiue ultra peti- 

 oluiu rufo; alis flavescentibus, apice grisescentibus. 

 % . Fronte carinato; clypeo aurantiaco, emarginnto, bidentato; mandibulis 

 flavis ; antennarum articulis 1-2 rufis, fascia fiava ; flagello subtus flavo- 

 annulato, apice cochleato, fiavo. 



Zethus Poeyi Sauss. Revue et Mag. de Zool. 1857, 270. 



Total length, 14 mm. ; wing, 10 mm. 



Head and thorax quite densely cribrose (moderate and a little 

 irregular often, in form of an oblique prick of pin). Ocelli pro- 

 minent, arranged in a rather large triangle. Vertex % forming 

 a ridge in form of a T, of which the vertical limb touches the 

 clypeus. The posterior part of the vertex a little more elevated 

 than the ocelli. Thorax contracted before, its margin little 



