ODYNERUS 



30: 



scutel before it becomes truncate, which is such that the post- 

 Bcutel is not touched by the truncation ; quite rounded, without 

 lateral angles, with a rounded, free, not limited fossette ; some- 

 times produced triangularly, convex, only parted by a longitudinal 

 or sulcate channel. 3d. Truncate or biangulate, with a very sharp 

 cavity and lateral angles (0. spinifer), but the post-scutel not 

 truncate. Even when quite rounded posteriorly, the metathorax 

 does not lose its lateral ridges, which extend from the posterior 

 wing to the articular valves of the abdomen, and which must not 

 be confounded with the superior and inferior edges which con- 

 stitute the lateral margin of the concavity, when existing. 



The abdomen has also various forms : 1st. In the elongate- 

 cylindrical type it is elongate and cylindrical, sessile, but the first 

 segment is bell-shaped, elongate, rounded, not or but slightly 

 contracted anteriorly, but not truncate ; as long as wide. This 

 form is very different from that of Divis. Odynerus, where the 1st 

 segment is wide, truncate anteriorly, its superior face being 

 always wider than long. 2d. Elongate, slender, but more 

 depressed; the 1st segment short, truncate, as in Odynerus, but 

 the post-scutel not truncate (0. spinifer-). 3d. More ovate, con- 

 tracted anteriorly, the first segment being small, cup-shaped, 

 rounded, not quite sessile, often subpetiolate ; the 2d segment 

 more swelled. 4th. Elongate spindle-shaped, quite slender, 

 attenuated anteriorly the same as posteriorly; the first segment 

 funnel-shaped, sometimes elongate and subpetiolate. 



The abdomen has a tendency to be more produced than in 

 Divis. ' Odynerus; and the 1st segment is always more coarsely 

 punctured than the 2d, which is just the contrary in Divis. Ody- 

 nerus. These various forms make quite insensible transitions 

 from one to another, and their various combinations make it very 

 K.aicult to define the subdivisions of the group, so that one must 

 pardon me if I have not succeeded in rendering them distinct 

 enough. 



The table of species, based on empirical characters, will perhaps 

 help the reader out of the chaos of the very numerous species, 

 better than the diagnosis of the subdivisions, and the following 

 table will assist in distinguishing the Stenodynerus from the 

 Divis. Pachodynerus and Odynerus pr. diet. 



