168 PROCEEDINOS OF THE NATIONAL MUSEUM. ^ol. 55. 



zygous condition, which is maintained until an accidental cross with 

 another group occurs. It must be stated, however, that one form of 

 dichroism appears to prevail within the limits of the colonies. The 

 black and red variegation of the legs, which gave rise in one species 

 to the name M. variegatipes, seems always to vary to a condition 

 (probably recessive) in which the black pattern is absent. Owing 

 to the existence of so many closely allied forms, the interpretation 

 of many of the published descriptions, often without the citation of 

 any exact locality, becomes very difficult. The United States Na- 

 tional Museum possesses a large collection of these bees received from 

 Dr. H. Friese, and I have followed his determinations whenever there 

 was no reason to the contrary. In a few cases I have been obliged 

 to dissent, and have given my reasons for so doing. 



XYLOCOPA FORMOSA Smith. 



A. female about 22 mm. long, from Mexico, D. F. (J. R. Inda, No. 

 52), appears to be large for this species, but it otherwise agrees, 

 especially in the striking characters of the head described by Maidl. 

 Is it possible that X. loripes Smith is the male of this species ? 



XYLOCOPA VIRESCENS Lepeletier. 



Alhajuelo, Canal Zone, May 29, 1912 (Busck). This is a species 

 of the X. hrasilianormin group, remarkable for its large size and 

 green wings. It agrees exactly with Lepeletier's measurement, and 

 although cited by Maidl as a synonj^m of l?rasiUano?'U77i, I believe it 

 is a perfectly valid species. There are three large black species with 

 similar green wings, separable thus : 



Disk of fix'st abdominal segment witli only feeble widely scattered punctures; 



anterior wing about 24 mm. long caUiclilora (Cockerell). 



Disk of first abdominal segment strongly and quite closely punctured 1. 



Third antennal joint longer; margin of scutellum before the truncation 



I'ounded; anterior wing about 23 mm. long rirescens Lepeletier. 



Third antennal joint shorter; margin of scutellum before the truncation rather 



sharp ; anterior wing about 19 mm. long transitoria Perez. 



Maidl also regards transitoi-ia as a synonym of hrasilianorum^ 



XYLOCOPA ARIZONENSIS Cresson. 



Tlahualilo, Durango, Mexico, two males at flowers of peach (A. W. 

 Morrill). 



XYLOCOPA SPLENDIDULA Lepeletier. 



Carcarana, Argentina (L. Bruner, No. 27). 



XYLOCOPA CILIATA Burmeister. 



Carcarana, Argentina (L. Bruner, Nos. 26 and 28.). The female 

 looks like X. colona Lepeletier, but is readily separated by the densely 

 punctured clypeus. 



