328 Tropical Zoology. (July, 
The great bulk of our author’s observations on animals 
and plants have been made, as the title-page informs us, 
‘in reference to the theory of evolution of living forms,”— 
in other words, to the views popularly included under the 
name Darwinism. ‘These views can scarcely be said to have 
met with fair treatment. They have been dolefully groaned 
over by certain “grave and reverend,” if not very ‘‘ potent 
seigniors,” on account of their supposed ‘‘ questionable 
tendencies,” almost in the very words applied in the days 
of Galileo to the heliocentric theory in astronomy. They 
have been sneered at by witling gallants by whom the hint 
of kinship with monkeys was felt as an ‘‘ owre true joke.” 
They have been “ gushed” over in the daily press by leader 
writers and special correspondents whose conceptions of the 
subject were of the haziest. The hostile critics of the 
evolution theory have been, for the most part, not naturalists 
but outsiders, incapabable of entering into the full meaning 
of the evidence. To take a case strictly analogous, what 
should we think of a lawyer who in a difficult and com- 
plicated matter should give a professional opinion founded 
on documents drawn up in a language with which he had 
but a very slight acquaintance? ‘‘ Theories,” says M. 
Dumas, ‘‘are like crutches; to judge of their value we must 
take them and try to walk with them.” This is what Mr. 
Belt does, and all who candidly read his book must concede 
that the doctrine of evolution throws a welcome light upon 
many abstruse phenomena, and brings into organic connec- 
tion facts which previously lay scattered in hopeless con- 
fusion. Let us take for example the phenomenon of 
mimetism—an unhappily chosen name—of which our author 
gives some interesting instances. 
A certain animal species is often found to show a super- 
ficial, but still striking and deceptive, resemblance to some 
other species, generally of a totally distinct group; to some 
vegetable product, or even to a fragment of lifeless matter. 
Instances of this are the ‘‘ walking leaves,” the moss insect, 
discovered and figured by the author, which closely simulates 
a few filaments of moss lying on the ground; the mimetic 
bug (Spiniger luteicornis), which in form, in the colouration 
of every part, and in its very movements mimics the hornet 
(Priocnemis). ‘This simulation, of course involuntary, enables 
the insect either to elude its enemies or to secure its prey. 
Thus the bug above mentioned might fall an easy victim to 
many birds and insects which would hesitate before attacking 
a hornet. Hence the bug owes its safety to its resemblance 
to the hornet. There is, again, a small spider which closely 
