ODYNERUS. 231 



A. All the segments except the first, bordered with yellow. 



These Odynerus have the body silky and adorned with beautiful 

 golden reflections, or they are covered with a velvety satin which 

 often conceals the punctures. They have a close resemblance 

 among themselves, so that, without comparing numerous speci- 

 mens, one easily confounds all under the same description, taking 

 them for the 0. nasidens of Latreille. This happened to me at 

 the beginning of my studies. When new specimens arrived, I 

 thought to distinguish many more species, and I have established 

 differences in the diagnoses which are far from satisfying me. 

 In fine, the increase of my collections has revealed to me such 

 differences of size, of color, and of details of form, that, after 

 having believed for a time that some species were distinguished 

 with clear precision, I have perceived that nothing is more 

 obscure than the limits of these species. A new examination of 

 my very numerous specimens, far from clearing up the chaos, only 

 results in filling me with new doubts ; for, contrary to what one 

 usually observes, the species do not appear to class themselves 

 according to their geographical distribution; in lieu of finding 

 one species from Mexico and another from Brazil, I find two 

 species equally diffused in the two divisions of the American 

 continent. In the midst of this confusion I think, however, that 

 I can distinguish the 0. brevithorax quite clearly, as there is 

 here quite a diffei'ence from other species, in the form of the 

 clypeus, etc. 



The appearance of these insects recalls very much that of 

 certain other Vespidse which have also their bodies velvety and 

 silky and which inhabit the same hot regions. Such as certain 

 Amistrocerus {A. Aristee, Parredesi); certain Nectarinia (N. 

 mellifiea), and even certain Chartergus (Ch. chartarius) ; with 

 which one should be careful not to confound the Odyneri 

 described below. 



a. Metathor ax forming a lateral angle on each side. 



66. O. toreviiliorax Sauss. — Niger, puuctatus, ubique tomento velu- 

 tino aureo-sericeo indutus ; thorace cubico, latitudine longitndini 

 aequali ; metanoto in tota latitudine excavato; ejus excavatione la?vi, 

 sericea, canthis acutissimis niarginata, utrinque in dentem lateralem 

 excurrentibus ; abdomine perfecte couico, sericeo ; priino seguieuto bre- 



