ODYNERUS. 143 



number of species of true Odynerus, of which, however, the pal- 

 pular articulations diminish quite regularly in size from the first 

 to the fifth (0. Iruncatus, 0. nasidens, etc.), so that this forma- 

 tion is not sufficient to characterize the genus. 



The true Rhynchium belong especially to Africa. I know in 

 America but one species which can figure in this group ; it is the 

 Rh. dorsale Fab., but even this species has not entirely the same 

 palpi with the Rhynchium, for the last three articles are too large 

 and the third is relatively too short. The Odynerus luctuosus 

 might from its palpi figure as well in the genus Rhynchium, as 

 the Rh. dorsale. 



Beside this, if the smallness of the last three and the lengthen- 

 ing of the second and third palpular joint should separate 

 generically the insect so distinguished, it would be necessary to 

 form quite a corresponding genus of the great African and Asiatic 

 Eumenes {vide Saussure Yespidas, I; pi. iv, fig. 2, b), and sepa- 

 rate generically,/. i., the E. conicus from the E. coangustatus, 

 which would be an impossibility. I see, therefore, no need of 

 adopting the genus Rhynchium in the description of the Ameri- 

 can fauna, the utility of doing which appears the less as it would 

 only free the genus Odynerus from one species. I have conse= 

 quently left this species in the latter genus. 1 



1. Rh* dorsale Fabr. — (Vide Odynerus dorsalis, p. 257). 



Gen. ODYNERUS Latr. 



Abdomen sessile or subsessile. Labial jmlpi 4-articulate. 

 Maxillary palpi 6-articulate. Mandibles elongate, as in Eu- 

 menes, more or less toothed. The second cubital cell not petio- 

 latc. 



This genus maybe distinguished by its elongated mandibles and 

 sessile abdomen. In numerous species, however, the abdomen is 

 subpedunculate, that is, the first segment is rather funnel-shaped, 



1 In my Studies on the Families of the Vespida I also desoribed as an 

 American Rhynchium the Rh, limbatum, p. 117, 27; pi. xv, tig. 10 (not 9). 

 But this typo, now in my possession, in consequence of the acquisition of 

 the collection of the late M. do Romand, appears to mo incontestable 



Asiatic. Like many others in this collection, it bore a wrong label. 



