66 Riley Presidential Address. 



Examination of these parts in other species of Apis fails to indicate any 

 particular modification or deviation in structure from mellifica. In Ajm 

 indica no differences whatever can be discovered ; in A. dorsata the leg is 

 somewhat more hairy and a few hairs occur on the outer surface of the 

 tibia. In A. florea the smallest species known, the spines on the apex of 

 the tibia are somewhat shorter and stouter and the hairs forming the cor- 

 biculum are somewhat less regular in length and arrangement. 



This statement of the structure of these parts in the species of Apis will 

 enable us to compare intelligently the similar parts in those genera most 

 nearly allied to them, tracing the variation through these to the more 

 widely divergent forms. The genera Melipona and Trigona include bees 

 which are closest to Apis in general structure and habits, and agree also in 

 the absence of the tibial spines of the posterior legs. We rind, as might be 

 inferred, a very close correspondence in the polliniferous apparatus, which, 

 in all essential details, is practically the same as in Apis. The pollen-col 

 lecting combs on the inner surface of the first tarsal joint are absent, or 

 rather their place is supplied by a uniform clothing' of short stiff spines 

 which are not arranged transversely in rows, as in Apis, but serve the same 

 purpose. This joint also differs in shape from that in Apis, by being sud 

 denly narrowed or excavated toward the base so that the nippers noted in 

 the former genus for the removal of the wax are practically wanting, 

 although the row of stiff spines at the apex of the tibia is still present, but 

 somewhat reduced. A very peculiar tuft of strong, curvet! spines occurs, in 

 the two genera mentioned, at the anterior outer angle of the tibia. This 

 has no counterpart in any other bees and its function is problematical. 



In the case of Bombus, the lowest of the social bees, there is at once a 

 greater divergence from Apis and at the same time a resemblence to it in 

 certain features of the hind legs and pollimferous apparatus. The tibial 

 spines are very strongly and prominently developed, allying this genus to 

 the solitary bees and other Hymenoptera, but the general structure of the 

 tjbia and first tarsal joint is practically identical with that of Apis, and the 

 tarsal joint in this particular does not present the divergence which was 

 noted in the case of the genera Melipona and Trigona, but has the broadly 

 truncated basal margin forming the lower blade of the nippers, even more 

 strongly developed than in Apis. The pollen-collecting spines on the inner 

 face of the tarsal joint are uniformly distributed over the surface, practically 

 as in the two genera last mentioned (Melipona and Trigona). The border 

 ing hairs of the corbiculum are somewhat stronger and more abundant, but 

 in all essential details the structure is identical with the same in Apis. 



The solitary bees of the genus Anthophora, which is somewhat nearer 

 Apis than any other, present distinct traces of the specialized polliniferous 

 apparatus of this last. The enlargement of the tibia and of the first tarsal 

 joint is quite marked, and the corbiculum is imperfectly indicated by the 

 longer growth of hairs on the edge of the tibia, the face of the latter being 

 also covered with shorter hairs. The brush or pollen comb on the inner 

 surface of the tarsal joint is practically the same as in Bombus. The small 

 row of spines at the apex of the tibia are entirely wanting, and the nippers 

 at the junction of the tibia and metatarsus are not particularly noticeable; in 

 fact this structure is not seen in any except the social bees which alone pro 

 duce and use wax in their economy. The genus Melissodes presents a dis 

 tinctly wider divergence from Apis, in that the hairy vestiture on the outer 

 surface of the tibia and metatarsus is equally long and dense over the entire 

 surface, showing little if any approach to the corbiculum, which, as we have 

 seen in Anthophora, begins with the shortening of the hairs on the outer 

 face of the tibia, In other particulars the bees of this genus are similar to 

 Anthophora, and in both genera the pollen collected is carried interspersed 

 among the hairs of the tibia and tarsus, being doubtlass emptied or combed 

 into them from the brush of the inner surface of the first tarsal joint, and 

 probably removed again by the same brush in storing it in their larval cells. 



Going still lower in the scale of bees, we find in Perdita a yet wider 



