450 Mr. T. D. A. Cockerell — Descnptions and 



Osmia subtrevorif, CklL, 1906. 

 Florissant, Colo., June 16, 1907 (S. A. Rohwer). 



Sphecodes (Machceris) Rohweri, sp. n. 

 ? . — Length a little over 5 mm. 



Head and thorax black, shining, with white hair, lohi'ch is 

 not at all infuscated dor sail y ; head transverse, front very 

 densely punctured, flagelluni thick, testaceous beneath ; 

 mandibles simple, ferruginous except at extreme base; disk 

 o£ mesothorax with strong punctures, ahout as close though 

 perhaps not quite so large as in S. Cressonii (the thorax itself 

 is smaller than in Cressonii, and not quite the same tint, 

 appearing a sort of blue-black by contrast) ; area of meta- 

 thorax semilunar, well defined, with strong radiating ridges ; 

 tegulse rufo-testaceous ; wings dusky reddish ; tarsi dark 

 brown, with glittering hairs. Abdomen shining, of a yellower 

 red than that of S. eustictus, the red including only the first 

 three segments (but these without black), the fourth and 

 following black ; second and third segments punctured 

 basally. 



Close to S. stygius, E,ob., from Illinois, but separable by 

 the characters italicised. 



Hah. Florissant, Colorado, at flowers of Salix hrachycarpa, 

 July 7, 1907 {S. A. Eohioer). Mr. Rohwer also took Pro- 

 ieraner rhots, Ckll., and Spheeodes Sophice, Ckll., at the flowers 

 of the same species of Salix, at Florissant, the first June 2, 

 the second June 6. 



While on the subject of Spheeodes, I take the opportunity 

 to offer a table of the larger species more or less like 

 S. dichrous. Many of these are very much alike superficially, 

 and are not easy to recognize without a table. The table is 

 based on females. 



When tlie abdomen is looked at from tlie 



side, a strong constriction is seen dorsally 



at the base of the second segment ; 



punctures of mesothorax strong and 



dense ; area with strong longitudinal 



ridges 2)^cosensis, Ckll. 



When the abdomen is looked at from the 



side, the constriction is seen to be feeble 



or absent 1. 



1. First abdominal segment with a blackish 



discal spot ; disk of mesothorax shining, 

 with the punctures widely separated . . 2. 

 First abdominal segment without a black- 

 ish discal spot 3. 



2. Area of metathorax with widely separated 



longitudinal ridges and a few cross ones ; 

 abdomen distinctly but not at all closely 



