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X. Monograph of the Genus Xylocopa, Lair. By 

 Frederick Smith, Assistant in the Zoological 

 Department of the British Museum. 



[Read 5th January, 1874.] 



There is no genus of bees, in the family ApidcB, that is 

 in my opinion more difficult of elucidation than Xylo- 

 copa ; the sexes of many species can only be correctly 

 assimilated when direct observation of their habits fur- 

 nishes the evidence necessary to wan-ant their union. 

 The males of numerous species are of a buff or fulvous 

 colour, whilst the females are totally black ; the sexes are 

 usually about the same size, but the males of some species 

 have very large approximating eyes, as in the case of the 

 drones of the hive bee, whilst others are quite lateral, 

 agreeing Avith those of the majority of the insect tribe. 

 Several other peculiarities distingvxish certain species of 

 this genus, such as the dilatation of the apex of the first 

 joint of the antennae ; and, in other instances, the inter- 

 mediate legs are elongated, agreeing in this respect with 

 several sj)ecies belonging to the extensive genus Ayitho- 

 phora. The females may be divided into two sections; 

 the first includes the majority of the species, and is distin- 

 guished by having the metathorax more or less rounded 

 posteriorly ; the second section have the same division of 

 the thorax abruptly truncate, the hinder margin of the 

 scutellum having a sharp edge, and being more or less 

 submarginate. 



Lepeletier de St. Fargeau has divided the genus into 

 sections : the first contains those species, the labrum of 

 which has three longitudinal elevated lines ; this is true of 

 his first species, but in the third the three elevations are 

 rather tubercles than longitudinal elevations. The second 

 section is said to be without elevated lines, and to be dis- 

 tinguished by having only a tubercle at the middle of the 

 base of the labrum ; this does not hold good as regards 

 many of the species placed in the section. I have dis- 

 sected several, and find in each three tubercles ; these are 

 not readily distinguished unless the labrum is detached 

 from the clypeus. Xylocopa Jlavo-rufa, and also X. 

 (estuans, have each three tubercles, and this I believe will 



TRANS. ENT. SOC 1874.— PART II. (aPR.) 



