738 Insects. 



or perhaps the egg deposited had proved unproductive. Repeated 

 observation proves the usual number of eggs deposited by O. bicolor 

 to be four, but sometimes as many as six. 



Having been furnished with ample details of the habits of three 

 species which construct their nests in shells, I shall proceed to give 

 them at some length. I am indebted to a friend residing at Bristol, 

 who has bred numbers of these bees, and who has kindly furnished 

 me with the result of his observations. I have also received shells, 

 from which I have bred Osmia tunensis myself. The species upon 

 which the observations of my friend were made, are Osmia bicolor 

 and O. tunensis ; the shells selected by these bees are those of Helix 

 hortensis and H. nemoralis : the shells are found partly hidden under 

 furze or dead grass, on the slopes of Durdham-down, near Bristol. 

 The number of cells formed in each shell varies a little ; the usual 

 number is four, but instances of six being found occur. I opened a 

 shell myself, containing six cocoons. The bee having found a shell 

 suitable to her purpose, deposits an egg, together with a suitable sup- 

 ply of pollen and honey, at the extremity of the tube ; the space 

 occupied thereby being about five lines in length : this space she clo- 

 ses by a thin partition, which is composed of abraded leaves or moss. 

 There is no lining of any kind to the sides of the tube. She repeats 

 this operation until she has constructed the required number of cells, 

 she next closes up the entrance to the tube, for which purpose she 

 collects pellets of earth, small pieces of stick, pebbles &c, which, be- 

 ing mixed with some liquid, probably gluten, secreted by the animal, 

 form a secure and ample protection to her works. The larva having 

 consumed the store laid up by the provident parent, spins a cocoon 

 of a toughish texture and of a dark brown colour ; the inner surface 

 is highly polished, and lined with a thin, delicate, membranous pelli- 

 cle, easily separable from the coarser exterior. About the third week 

 in March, should the weather prove favourable, Osmia bicolor, hav- 

 ing arrived at its perfect state, makes its appearance ; O. tunensis is 

 a fortnight or three weeks later. The discovery of this singular vari- 

 ation in the habits of these species was made some years ago ; what 

 led to it was watching the female flying about the furze, and eventu- 

 ally alighting on what proved to be a shell containing a nest. A few 

 weeks ago, another species, Osmia spinulosa, was discovered in the 

 act of forming its nest in a snail-shell. This was at Swanage ; and 

 the discovery was made by Mr. Lighton, who has subsequently found 

 shells in some numbers, containing the nests of this bee. I have 



