ORTHOPTERA. 
221 
the eggs , or could possibly promote their maturation 
if it were. The temperature of the body of a cold 
blooded animal is always in equilibrium with the sur- 
rounding element, and it could, therefore, impart no 
additional heat to objects subjected to the same in- 
fluence in this respect as itself. The case is different 
when multitudes are congregated within a narrow 
space ; heat is then generated, as is well known to be 
the case in bee hives. 
Fam. Blattid^:. 
The members of this family are very unlike the pre- 
ceding, and they may be said to differ nearly as much 
from all the other tribes with which they are asso- 
ciated. Their bodies are in general broad, oblong, 
and depressed, the abdomen almost completely covered 
by the tegmina, which considerably overlap each other 
on the back, and wholly cover the under wings. The 
head is curved inwards beneath the prothorax ; the 
antennee very long, setaceous, and flexible, inserted 
in a notch in the inner side of the eye ; the two lower 
joints of the maxillary palpi are somewhat globular, 
the terminal one (as is likewise the case with the 
corresponding joint of the labial palpi,) pretty thick 
and truncated. A conical and articulated appendage 
projects from each side of the abdomen behind. The 
legs are thickly armed with spines on the tibia, and 
all the tarsi consist of five joints. 
Most of these insects are of a uniform brown colour, 
a hue well adapted to their habits and the nature of their 
haunts. A few, which usually frequent flowers, are 
