Miscellaneous. 165 
rent species. Outside, the ootheca is of a greyish-brown colour. It 
is generally pyriform, with the smaller extremity upwards; it ap- 
pears to be strongly furrowed transversely. If we make a section 
in the direction of these furrows, we observe that the eggs are con- 
tained in a circular median chamber. ach of the large exterior 
furrows corresponds to a story; and an ootheca contains some 
twenty stories. 
This median chamber is surrounded by frothy envelopes without 
eggs, the arched layers of which correspond to the succession of 
stories of the central chamber. ach story of this chamber is 
divided into two cells by a thin antero-posterior partition, and com- 
municates in front with the exterior by a sort of flattened neck, the 
edges of which, in the form of scales, are bent and laid one over the 
other ; that is to say, they are imbricated. 
The eggs in each cell are symmetrically arranged, in such fashion 
that the portion of the egg which will constitute the extremity of 
the abdomen is applied to the wall, whilst the heads are turned 
forward obliquely and are all brought close together. Consequently 
the larve, to get out, will only have to advance straight forward, 
without any turning. Lach central cell contains a dozen of eggs; 
there are about twenty-four on each story, each contained in a 
sort of gummy alveolus; the cells at the two extremities of the 
case contain a smaller number. This egg-case, which is at first 
transparent and frothy, solidifies and becomes impermeable to 
such a degree that it may be immersed in water without wetting 
the eggs. f 
To construct its egg-case the insect employs its abdomen and 
elytra. Clinging to the branch of a shrub, the Mantis secretes a 
frothy, slightly transparent liquid, which it holds up by means of 
the extremity of its elytra. By this means it can construct the 
first stories of its egg-cases in the form of a spherical hood by 
means of the regular movements of its abdomen, which kneads the 
frothy substance and spreads it in successive layers with the assist- 
ance of the cerci. The eggs are expelled by the abdomen, together 
with a certain quantity of frothy liquid, which will form the alveo- 
lus. The ootheca gradually acquires a darker colour and becomes 
harder. 
After the copulation, which generally takes place in September, 
the female builds her ootheca. The eggs hatch in May and June. 
Last month I witnessed the emergence of the larve from the 
oothece that I brought with me. Lach larva, while still soft, 
advances towards the aperture of its cell in order to issue from it. 
M. de Saussure explains the emergence of the larva in the fol- 
lowing manner :—* The little larva has now to escape from the cell 
in which it is enclosed; and as zt 1s too weak to make use of its feet, 
nature comes to its assistance by means of a peculiar artifice. The 
surface of its body is clothed with a chitinous substance, upon which 
are developed some spines directed backward. By giving its abdo- 
men an undulatory movement, the spines serving as a support 
