ODTNERUS. 361 



parts also variable : the antennae in the majority of species rather 

 short, filiform, the apical joints in the male with a small hook, or 

 spirally rolled ; mandibles blunt with blunt teeth, never long as 

 in Eumenes ; labial palpi stout, 4-jointed, and covered with stiff 

 hairs ; maxillary palpi (>-jointed, diminishing in length to the apical 

 joint, Avhich, however, is sometimes longer than the 5th joint, the 

 apical three joints united, distinctly longer than the 3rd. Thorax 

 rounded or truncate both anteriorly and posteriorly, in a few 

 species emarginate posteriorly ; legs short, somewhat feeble and 

 slender, intermediate tibite with one apical spine ; claws dentate. 

 Wings : in the fore wing the form and proportions of the radial 

 and cubital cells are variable; in general, however, the radial cell 

 is widely subtriangular, the apex acute, or slightly truncate and 

 appendiculate ; three cubital cells, the 2ud receiving both recur- 

 rent nervures. Abdomen of variable shape, the basal segment 

 often narrowed, but never fashioned into a long petiole as in 

 Eumenes, always more or less covering over the base of the 2nd 

 segment. 



The genera Rhynehium and Odi/nerus are only clearly separable 

 by an examination of the mouth-parts, as noted in the key to the 

 genera. Externally the tMO genera resemble each other and grade 

 one into the other astonishingly. Roughly, however, the species 

 of lihj/ncMum are larger, heavier built insects than the species of 

 Odynerus. Both genera can at once be distinguished from Eumenes 

 by the form of the basal abdominal segment, which is never 

 narrowed into an elongate petiole, but, though often constricted and 

 narrower than the 2nd segment, always receives and more or less 

 covers over the base of the latter. 



The species of Odyneri make sometimes little thin clay shells 

 for nests, but more often make use of crevices and holes for their 

 nurseries, storing as food for their larvae the caterpillars of various 

 species of small moths. I have never found them attacking or 

 storing spiders or other prey. 



Key to the Species. 



A. First abdominal segment with one, some- 



times two transverse sutures near the base. 



a. Colours black and red O. sikhimensis, p. 363. 



b. Colours black and yellowish white O. sichelii, p. 303. 



c. Colours yellow and ferruginous brown .... O. amadanensis,T^.'iQ-^. 



B. First abdominal segment without a suture, 



a. Colours reddish or ferruginous and yellow, 

 a' . Margins of all the abdominal segments 



more or less yellowish O. omatus, p. 364. 



h' . Sec(md to fourth abdominal segments [p, 365. 



yellow . . O. punctatipennis, 



c'. Second abdominal segment only yellow, 



rest reddish brown O. 2Mnctum, p. 365. 



b. Colours black and yellow, or black and 



yellow and red. 



