22 HYMENOPTERA CHAP. 



has ascertained that a few of the very numerous Hawaiian species 

 of the genus are really parasitic on their congeners : these parasites 

 are destitute of a peculiar arrangement of hairs on the front 

 legs of the female, the possession of which, by some of the non- 

 parasitic forms, enables the bee to sweep the pollen towards its 

 mouth. These observations show that the structural peculiarities 

 of Prosopis are correlative with the habits of forming a peculiar 

 lining to the cell, and of gathering pollen by the mouth and 

 conveying it by the alimentary canal instead of by external parts 

 of the body. Prosopis is a very widely distributed genus, and 

 very numerous in species. We have ten in Britain ; several of 

 them occur in the grounds of our Museum at Cambridge. 



The species of the genus Colletes are hairy bees of moderate 

 size, with a good development of hair on the middle and posterior 

 femora for carrying pollen. They have a short, bilobed ligula 

 like that of wasps, and therein differ from the Andrenae, which 

 they much resemble. With Prosopis they form the group Obtusi- 

 lingues of some taxonomists. They have a manner of nesting 

 peculiar to themselves ; they dig cylindrical burrows in the 

 earth, line them with a sort of slime, that dries to a substance 

 like gold-beater's skin, and then by partitions arrange the 

 burrow as six to ten separate cells, each of which is filled 

 with food that is more liquid than usual in bees. Except in 

 regard to the ligula and the nature of the cell-lining, Colletes has 

 but little resemblance to Prosopis ; but the term Obtusilingues 

 may be applied to Colletes if Prosopis be separated as Archiapidae. 

 We have six species of Colletes in Britain. 



Sphecodes is a genus that has been the subject of prolonged 

 difference of opinion. The species are rather small shining 

 bees, with a red, or red and black, abdomen, almost with- 

 out pollen-collecting apparatus, and with a short but pointed 

 ligula. These characters led to the belief that the Insects are 

 parasitic, or, as they are sometimes called, cuckoo-bees. But 

 evidence could not be obtained of the fact, and as they were seen 

 to make burrows it was decided that we have in Sphecodes 

 examples of industrial bees extremely ill endowed for their work. 

 Eecent observations tend, however, to prove that Sphecodes are to 

 a large extent parasitic at the expense of bees of the genera 

 Halictus and Andrena. Breitenbach has taken S. rubicundus out 

 of the brood-cells of Halictus quadricinctus ; and on one of the few 



