In the southwestern United States there is a form which has been 

 described under the name exuberans. Many specimens of this form 

 appear quite different from tjrpical similis — the punctures of the 

 pronotum are more coarse and dense, the pronotum is narrower, the 

 distal enlargement of the paramere is smaller, and the indentation is 

 gradual and not abrupt. Viewed apart, this form does appear to be 

 a distinct species, but the complete picture shows it is connected with 

 other similis forms by an intergrading series. The shape of the 

 pronotum and genitalia appears to be merely an extreme extension 

 of the clinal trend described above, and southwestern specimens are 

 more similar to specimens from western Nebraska, Kansas, Texas, 

 and eastern Colorado than to eastern populations. The narrower 

 pronotum and smaller genitalia are characteristic of the western popu- 

 lations; furthermore, in the same locality one finds typical "exu- 

 berans" types intermediated with clear intergrades to typical similis. 

 Specimens have been seen with the coarse pronotal punctation of 

 "exuberans," typical similis genitalia, and others with the opposite 

 combination. Some are intermediate between the two forms in both 

 features. Females possess the "spiny" bursa and are quite like other 

 similis females except that generally they have coarser pronotal punc- 

 tation. It therefore appears that "exuberans" is a synonym of similis 

 and represents a geographical variant not defined well enough to 

 justify segi'egating it as a separate taxon. (A similar, though less 

 well documented, trend to larger pronotal punctures and a narrower 

 pronotum was also noted in communis from the Southwest.) 



Most specimens identified by Mr. Lane or by us will be labelled 

 in collections as M.Jissilis Say. 



2. Melanotus spadix (Erichson) 



Figures 4e, 8e 



Cralonychus spadix Erichson, 1842, p. 103. 

 Melanotus spadix. — Candfeze, 1860, p. 354. 

 Melanotus abdominalis of authors, not Erichson, 1842. 

 Melanotus decumanus. — Dietrich (not Erichson), 1945, p. 55. 



Male. — -Large species, body color reddish browTi to dark reddish 

 brown, covered with yellowish hau's evenly distributed over body. 



Head: Front coarsely punctate, most punctm'es hexagonal shaped, 

 distance between punctures less than half puncture diameter, surface 

 sometimes with slight, broad depression anteriorly, frontal margin 

 evenly convex, not strongly protuberant; parantennal fovea very 



