220 Journal New York Entomological Society. [Voi. xxiv, 



grayish-white on the back and sides, producing a sooty aspect ; scu- 

 tellum wide, with few punctures, especially in its anterior half, post- 

 scutellum very narrow. 



Abdomen black and not elongate, well punctured except along the 

 middle of the segments, finely so on the sides; pilosity dense and white 

 on the first segment and on the hind margin of segments two, three, 

 four and five, except in the middle, black everywhere else ; epipygium 

 narrow at the base, spines large. 



Wings subhyaline, of a brassy tint, tegulee brownish black. 



Legs black; hairs yellowish white on the intermediate and poste- 

 rior tibiai and tarsi exteriorly, brown on the inner side of the fore 

 tarsi, otherwise black; tibial scale small, anterior tooth very pointed 

 and long, posterior tooth A^ery rounded and short. 



Male. — This sex differs from the female as follows : Head yellow 

 on labrum, clypeus, frontal shield, a large spot at the base of the 

 mandibles, and some mixed with the black on the lateral downward 

 projections of the frons between the clypeus and the eyes; head and 

 face narrower; mandibles smaller, with only two teeth present (at 

 the apex) ; labrum with only one tooth or lobe; clypeus with fewer 

 punctures ; ocellar pits very small or even obsolete ; vertex more nar- 

 rowed and flattened. Thorax as in the female. Abdomen differs in 

 having a patch of long, white hairs on the sides of segment six. A 

 pair of cercus-like pieces (penicilli) present on the top of the seventh 

 dorsal segment. Tibial scale not much smaller than that of the 

 female, but with only one lobe. 



Type. — Probably in the British Museum, 



Distribution.- — Mexico; Brownsville, Texas; Utah. 



Variations. — A male from Washington Co., Utah, differs from the 

 typical male described above by having the hairs of the head and 

 thorax entirely white and much denser, while the white hairs of the 

 abdomen occur only along the sides. 



Xylocopa aztcca Cresson is a form very similar to tabaniformis, 

 and there seems to be no reliable structural character upon which the 

 two forms can be separated. Azteca female differs from the female 

 of tabaniformis by the presence of white pilosity on segments one, 

 two and three of the abdomen only, but this variation between the 

 two forms seems to be constant. The males of these two forms show 

 even less variation ; they differ as follows : the white hairs of the 



