1896.] ENTOMOLOGICAL XF.XVS. 159 



great variation in size, yet the specimens are identical in other 

 respects. 



Oxybelus emarginatus Say. 



I have numerous specimens of this very variable species from 

 the East and from Colorado. The following, which I find com- 

 monly in specimens contained in my collection, may be added to 

 the specific characters given by Robertson. Lateral point of 

 squamae minute, not exceeding (rarely attaining) tip of squama ; 

 spine usually somewhat longer than broad, sides gently rounded; 

 rnetanotum above with strong oblique striae, reticulate immedi- 

 ately below the spine, with a small, well-defined, triangular area 

 above and joining the large, median, triangular area. Lateral 

 faces closely finely punctate or striato-punctate; median area long 

 triangular, smooth or faintly striate within; metapleurae finely 

 punctato-striate, sometimes smooth at the middle ; last dorsal 

 segment in female short, triangular, very slightly emarginate at 

 tip; last dorsal segment in male short trapezoidal, truncate api- 

 cally. 



O. sparideus Ckll. (Trans. Amer. Ent. Soc. xxii, 292) as it 

 stands at present, is a synonym of emarginatus. There is nothing 

 in the description to separate it. In a note below, the description, 

 Mr. Fox says it differs in the form of the spine and coarser punc- 

 turing. A detailed drawing of the squamae and spine of spa- 

 rideus received from Prof. Cockerell, shows the form usual in 

 emarginatus. The difference in the puncturing as here exhibited 

 would not alone be sufficient to separate them. 



I have found three forms in Colorado, all very closely allied to 

 emarginatus, but presenting structural characters which render 

 it impossible for me to unite them at present. I give herewith 

 comparative descriptions of these three forms. Such is the wick- 

 divergence in structural characters that I do not believe either 

 intermedius or dilutus will prove to be the female of coloradcnsis. 

 Material collected by Prof. Cockerell, in New Mexico, and de- 

 termined by Mr. Fox as emarginatus, should probably be referred 

 to one of these forms, 



Oxybelus dilutus n. sp. Differs from cniarginafns as follows: Female: 

 mesonotum and scutellum sparsely punctured; squama; with lateral points 

 large, strong, nearly straight, scarcely equaling tips of squama.-; spine 

 strongly narrowed to the base; metathorax above with oblique stria-, m> 



