ODYNERUS. 31? 



more finely punctured. Abdomen cylindrical, the first segment 



in form of an elongate bell, as wide as the second, rounded ante- 

 riorly, with a feeble depression above; the second constricted at 

 base; its posterior edge very deeply and suddenly canaliculate, 

 with its margin very strongly reflexed, like an erect lamella ; the 

 very deep channel very coarsely punctured. The other segments 

 finely punctured, not reflexed. 



Black. A ferruginous spot at base of the antennae; a frontal 

 spot, a dot in the sinus of the eyes at a post-ocular spot, a. sub- 

 marginal fascia on the anterior edge of the prothorax, a spot 

 under the wing, margin of tegulaa, a spot on mesothorax before 

 the scutel, post-scutel, and inferior edges of metathorax, dull 

 •ferruginous or yellowish. The first, two abdominal segments 

 margined with a regular yellow band, and adorned near the base, 

 each with two lateral yellow or ferruginous spots ; the spots of 

 the first segment a little oblique. Feet black ; knees and tarsi 

 beneath ferruginous, or yellowish. Wings subhyaline, nerves 

 fuscous. 



Var. a. Prothorax with only two yellow spots ; disk of meso- 

 thorax not spotted. 



b. The free spots of the 1st and 2d segments of the abdomen 

 wanting. 



%. Smaller. Vertex having a large double tubercle; this is 

 flattened and polished, parted by a groove. Clypeus polygonal, 

 longer than wide, yellow, terminated by two acute teeth. Scape 

 of antennae beneath, inner orbits and frontal spot, yellow. Hook 

 of the antennae black. Mandibles with a yellow line. Second 

 abdominal segment slightly swelled ; the free spots of the first 

 two segments often wanting in the small specimens, especially 

 those of the 2d segment. Tibiae and tarsi. yellowish-ferruginous. 

 Metathorax generally black, except the valves of the articulation. 



Var. In small specimens the tubercles of the vertex are quite 

 obsolete. — The males are sometimes very small. Length, 7 mm. ; 

 wing, 5 mm. 



Bess. a. diff. — This species has intermediate forms between O. 

 vagus and 0. conformis ; it is a little mere elongate and slender 

 than the first.; a little less than the second. It is vorv neatly 

 characterized by the strong difference o( form oi' its 2d abd. seg- 

 ment, the edge of which Is extraordinarily deeply and narrowly 

 canaliculated as in no other species, except Ancistrocerus Ar 



