2G8 HYMENOPTERA OF AMERICA. [PART 1. 



Insect of a shining black, clothed with a fine grayish pile ; a 

 spot behind each eve, two great spots on the prothorax, two on 

 the metathorax, post-scutel, and the superior face of the first 

 abdominal segment, of a whitish yellow (the hand of the first s< g- 

 ment often notched with black); wings of a deep violet-brown. 



%. Thorax more strongly cribrose. Clypeus white, wider than 

 long, polygonal ; its inferior border straight truncate, not biden- 

 tate, finely bordered with black, a spot on each mandible, a mark 

 on the front, another on the scape of each antenna, a dot under 

 the wing, whitish. Antennae terminated by a brown hook, a little 

 rolled at the end. Second abdominal segment adorned on each 

 side near its base with a transverse whitish spot. .Haunches, 

 tibiae, and knees spotted with white. First abdominal segment 

 wholly white above. 



Ress. a. cliff. — This Odynerus astonishingly resembles the 

 Monobia quadridens, and it is rare to find two as distinct species 

 which offer so close a likeness. The 0. bidens differs from the 

 Monobia quadridens, by its maxillary palpi composed of six 

 articles, 1 and its labial palpi of four distinct articles; the fourth 

 being articulate; by its clypeus, which is abruptly truncate in 

 both sexes, and neither a little notched nor bidentate, and which 

 is not excavated at the extremity with the female; by the post- 

 scutel, more truncate, not bimammelonate, and by the very dis- 

 tinctly punctured flat baud of the 2d segment; by the white spots 

 of the metathorax (a character probably of little stability). 



The 0. i-sectus has a livery similar to the O. bidens, but it 

 possesses neither the metathoracic teeth, nor the sharp lateral 

 ridges. 



Hob. The southern United States. 1 9 from Florida (E. 

 Norton); a % from Tennessee (E. Falconet, Preudenreich). 



Observation. — As this description is based solely on one indi- 

 vidual of each sex, it may not apply to all specimens brought from 

 localities distant from each other. It is probable that the male 

 does not always offer the very singular lateral spots of the 2d 

 segment. 



//. Mi hitJi'imx more flattened; the superior edges roughened, not acute. 

 91. O. Alvaradi Sacss. — Niger, velutinus, confertim pnnctatns ; 

 abdomine conico, aureo-serieeo, marginibus crasse purietatis ; metanoti 



1 The maxillary palpi have here the ordinary form which they assume 

 among the Odyneri ; the articles 2, 3 are not slender ; the (5th is lengthened. 



