414 Messrs. T. D. A. Cockerell and W. Porter on Bees. 



flagellum brown beneath, except at the extreme base ; vertex 

 somewhat roughened ; mesothorax dull, densely and strongly- 

 punctured ; base of nietathorax evenly and delicately longi- 

 tudinally ridged ; pubescence of thorax grey above, white on 

 pleura and sides of nietathorax ; tubercles dark ; protliorax 

 with a small yellow line on each side of the hind margin ; 

 femora black, with yellow knees ; tibiae yellow in front and 

 black behind ; basal joints of tarsi cream-colour, of hind tarsi 

 blackened behind ; small joints brown ; teguhy brownish 

 hyaline ; wings clear, nervures and stigma dark brown ; 

 stigma almost obsolete ; marginal cell appendiculate ; second 

 submarginal long, narrowed about half to marginal, receiving 

 the first recurrent nervure about tiie end of its basal fourth, 

 and the second about the beginning of its apical sixth ; 

 abdomen very closely punctured, the liind margins of the 

 segments pallid, with very thin hair-bands ; hair at apex 

 white. 



Hah. Las Vegas, N. M., at flow^ers of Grindelia squarrosa^ 

 Aug. 9 and 14 ( W. Porter) ; also one at flowers of Verbesina 

 encelioideSj Aug. 12 {CklL). 



Perdita, Smith. 



Mr. Ashmead, in dividing the old genus Perdita, has used 

 the relative lengths of the joints of the labial palpi for 

 diagnostic purposes. In some groups the first joint is twice 

 the length of the other three together, or even more than 

 twice, while in others it is not nearly so long. In the 

 following table we give the measurements in /i of a number 

 of labial palpi ; first the length of tiic first joint, then that 

 of the other three together, then the latter in percentage of 

 the former : — 



First joint. Last three. Vo- 



P.{Tetraperditd) seAmaculata,Q\i\\ 430 ir;0 34 



P. spheeralcece, Ckll 750 280 38 



P. {CockerelUu) verbesince, CkW 800-900 370-380 42-4G 



P. {Cockerellia) alhipennis, var. liydUna, 



Cress 1050 500 47 



P. (rentaperdita) albovitiata, Cldl 680 330 48 



P.saUcis,Cm 350 180 51 



P. affinis. Cress 760 430 56 



P. sidce, Ckll 350 200 57 



P. (I'erditella) larrea-, Cldl 420 240 57 



P. Tmcnsendi, Ckll 800 470 58 



P. rhodura, Ckll 500 300 (10 



P. U'ontonfP, Ckll 580 .31»0 «7 



P. Ivteola, Ckll 450 310 m 



P. phaceli<r, Ckll 3.30 220 HO 



