( 247 ) 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.)
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