236 INSECTS. 



similar plates at the base of the thorax. The wings 

 have two submarginal cells. 



The third family, Dasygastrce (i.e., the hairy-bellied 

 Bees), is distinguished by a dense clothing of hairs 

 forming a pollen brush on the underside of the abdomen 

 of the female, and by the very large upper lip, which 

 last, with the spines which terminate the abdomen in 

 the males, suffices to mark these also.* 



In all the genera except Ceratina, the submarginal 

 cells are two in number. 



This family contains some of the most interesting 

 insects of the whole tribe ; and perhaps a greater variety 

 of architectural contrivances is found in it than in any 

 other family. 



Some species of Osmia, the first genus, have obtained 

 the name of Mason Bees, from their use, in the for- 

 mation of their cells, of a cement composed of small 

 stones, grains of sand, &c., agglutinated together ; but 

 this habit is not confined to, nor indeed most remarkable 

 in, this genus. 



The reader will require no apology for the quotation 

 of a passage in the interesting " Catalogue" of Mr. Smith 

 upon this genus. 



" If I were asked what genus of Bees would afford 

 the most abundant materials for an essay on the diversity 

 of instinct, I should, without hesitation, point out 

 the genus Osmia. The most abundant species is O. 

 bicornis (PL IX., fig. 5). Its economy is varied by cir- 

 cumstances. In hilly countries, or at the seaside, it 

 chooses the sunny side of cliffs or sandy banks, in which 

 to form its burrows ; but in cultivated districts, particu- 



* In Ceratina, tlie last genus, this pollen brush is wanting. 



