398 
The description of the egg applies in every particular to 
the specimens now exhibited, but on Mr Clegram’s pebbles, a 
large number of the eggs have lost the “couvercle rayonné,” 
and show either the spherical egg contents within the lower 
shell, of a rich crimson purple colour; or these too are gone 
and only the thin hollow hemispherical cup of white chitine 
remains. These latter are iridescent, so that-a small batch of 
the eggs, some perfect, some like cups with crimson balls 
within, and others, empty iridescent shells, forms a very strik- 
ing object under a low power. 
Hermann’s figure of the eggs (two in number) has been 
copied in Loudon’s Magazine of Natural History, but gives no 
idea of their beauty. 
Gervais says the eggs may be occasionally seen on stone- 
work in the streets of Paris. 
In the Entomologists’ Monthly Magazine, (1867-71,) Mr 
Miiller notices the Mite itself in countless numbers on flint 
gravels near Elmersend, and its eggs have been noticed on other 
occasions in Britain.* 
The egg is about the ;3,th of an inch in diameter, so 
that a square inch of surface might contain over 25,000. I 
actually counted 16,000 on one square inch of this particular 
pebble, [Mr Clegram’s two acres might harbour 3(10").] The 
temperature of the 8th, 9th, and 10th January, 1872, varie | 
from 34° to 38° Max., 28° to 32° Min., and it is remarkable 
that at such a time, the female Mites should deposit their eggs, 
as there appears to be little doubt they then did. 
Mr Clegram took these eggs to be organisms of a vegetable 
nature, and did not therefore look out for any of the Mites 
themselves, nor attempt to hatch any of them. 
Hermann and Koch have described some 20 species of these’ 
Sociable Mites (Trombidide,) of the genera Tetranychus and 
Petrobia, only a few of which have been described from Britain. 
They feed on plants, on the plum, elm, willows, guelder rose 
and nettle, and spin delicate webs of silk, on which they live 
in dense societies. 
* Proceedings of the Bristol Microscopical Society. 
