ODYNERUS. 343 



All the abdominal segments regularly margined with ochre- 

 yellow; the anal segment yellow or margined with yellow. The 

 fasciae rather wide ; the first being the narrowest. Feet black; 

 tibiae a little spotted with yellow, often yellow anteriorly ; tarsi 

 slightly ferruginous. Wings ferruginous with the extremity 

 smoky. 



Var. a. The body grayish-velutinous or fulvo-velutinous. 



6. Clypeus quite black. 



c. Angles of prothorax scarcely dentiform. 



d. A little yellow marginal line on both sides of the lower 

 part of the excavation of the metathorax. 



e. Anus black. 



%. Clypeus rather pyriform-elongate, bidentate, white or lute- 

 ous, as also the frontal spot and the inner orbit of the eyes. 

 Antennae beneath yellow or fulvous ; the hook arcuate, black. 

 The 7th abd. segment only, margined with yellow. 



Var. a. Clypeus obtusely bidentate. 



b. Anus not margined with yellow. 



An examination of numerous specimens has shown notable 

 differences in the form of metathorax: 1°. Sometimes it is quite 

 widely excavated, the lateral parts forming very salient borders, 

 or it is even rather angulate on each side. The strong rugosities 

 form sometimes a sort of arched edge, margining the fossette 

 superiorly; sometimes they have a tendency to delineate angular 

 ridges margining the cavity, making this bipentagonal as in the 

 true Ancistrocerus {A. capra, etc.). — 2°. In other specimens the 

 metathorax is not so angulate, nor so excavated ; its side margins 

 are not so produced, but it is more rounded; the fossette is 

 smaller and rounded, more closed and confined by the rugosities. 

 This is more frequent in the males. 



These various forms greatly embarrassed me until I could com- 

 pare numerous specimens. It is important to notice that the 

 principal character of this species is the very rugose sculpture of 

 the metathorax, its form being variable. It is still more rugose 

 and excavated than in 0. mystecus. 



Reus. a. diff. — A distinct species, well characterized by its 

 metathorax, as just indicated; by its bidentate prothorax, and 

 the abundant yellow marginal ion of the abdomen, and anus, often 

 yellow. 



In the nialedhe antenna 1 , yellow beneath, recall the 0. Huas- 



