УИ Е 
It is of interest, that Xylocopae may sometimes be found wintering 
in underground nests of bees of the genus Anthophora (Friese 1901); 
thus, they are returning into the same conditions, where their ancestors 
have lived. 
The rapid metamorphosis of the Ceratina and the Xy/ocopa, as well 
as the prolonged imaginal period of life, must evidently be connected 
with this phenomenon of migration. 
The easy access of humidity and mould into the nests built in half 
decayed wood, forced the insects to look for new refuges for their nests. 
From this moment, two separate currents in the history of the A'ylo- 
copa and Ceratina are arising. 
Some bees began to settle in drier and consequently harder wood; 
in course of time typical Xy/ocopae developed from these, the biggest and 
strongest bees in the world. The other began to settle in the tender 
pith of various stems where the chance of finding a suitable lodging is 
the greater the smaller the nest-builder is himself. 
As a result, we see that the Ceratinae are, generally speaking, small 
bees, and that the smallest solitary bee existing is a Ceratina (С. par- 
vula Friese 1891). 
The Ху/осорае have, even in these new conditions, conserved some 
traces of the branched structure of their nests; as for the Ceratinae, their 
nests have entirely lost these characters, which is easy to understand con- 
sidering the mechanical constitution of their new abode. 
As to the genesis of double septae in the nests of Ceratina callosa, 
which is very instructive from the point of view of the evolution of instincts in 
wasps and bees, the author is of the same opinion, as he has been when 
describing similar constructions of wasps of the genus Odynerus (Ма- 
Iyshev 1911). 
Списокъ цитируемой литературы. 
1894. Ashmead, W. The habits of the aculeate Hymenoptera. Psyche, 
vol. УП. 
1896. Aurivillius, Chr. Ueber Zwischenformen zwischen socialen und 
solitären Bienen. Zoologiska Studier, Festskrift til Lilljoborg, Upsala. 
1903. Buttel-Reepen. Die stammesgeschichtliche Entstehung des Bie- 
nenstaates. Biolog. Centrabl., Bd. 23. — Separ. Leipzig, 1903. 
1895. Comstock, J. H. and A. В. A manual for the study of insects. 
1840. Dufour et Perris. Mémoire sur les insectes Hyménoptères qui 
nichent dans l'intérieur des tiges sèches de la ronce. Ann. Soc. Entom. 
France, v. IX. 
1906. Фабръ (Fabre, J. Н.). Инстинктъ и нравы насфкомыхъ. Перев. 
съ франц. Е. И. Шевыревой, т. |, 2-ое изд. 
1901. Ferton, Ch. Notes détachées sur instinct des Hymenopteres 
melliferes et ravisseurs avec la description de quelques espèces. Ann. Soc. 
Entom. France, v. LXX. 
1877. Frey-Gessner, E. Hymenopt. Excursionen. Ent. Nachr., Bd. 3. 
