THE 
WEEKLY ENTOMOLOGIST* 
“ENTOMA QUIDQUJI) AGENT NOSTKI EST FARRAGO LIBELL1.” 
Vol. 2. No. 24] SATURDAY, JULY 25, 1863. 
HOMOLOGY. 
Y\NE of the most important re- 
^ suits of the study of science, 
is that we are enabled to see things 
as they are, and not as they seem 
to be. Entomology affords some 
most interesting- examples of this 
truth. At first sight every order of 
insects appears to be formed in 
agreement with a separate class of 
type. On closer examination, how- 
ever, it is found that there are four 
great types in zoology — ver! ebrafa, 
articulata, radiata, and mollusea, 
and between any of the various 
forms which make up any one of 
these grand div'sions, homologies 
may be traced Ear otherwise is it 
if we attempt to ti-ace any homology 
between one of these main types 
and another. This is emphatically 
“ no go.” The mouth of an insect 
is not homologous with the mouth 
of a mammal, though it is with the 
mouth of a spider. It is quite a 
mistake to suppose that identity of 
functions is sufficient to establish an 
homology between the organs of 
two different creatures. There must 
be similarity of structure. For 
[Price 2 d . 
even in the same sub-kingdom an 
homology cannot always be traced 
between parts appropriated to similar 
uses. For example, the gill of a 
fish is not homologous with the 
lung of a mammal. The proper 
term for the sort of agreement 
which exists between parts appro- 
priated to the same uses, but differ- 
ing radically in structure, is analogy 
and not homology. Confining our- 
selves within the limits of entomo- 
logy, we shall observe, that, as 
homologies may be traced between 
insects and other articulata, so may 
they be found between different 
orders. Let us look at the mouth 
of a mandibulate insect, beside that 
of a flea. At first there is no point 
of agreement between the two. In 
the mouth of a beetle we recognize 
the mandibles as a strong pair of 
upper jaws, varying in form and 
size according to the habits of the 
insect. Beneath are the less for- 
midable maxilla). The labrum and 
labium naturally suggest the ideas 
of an upper and under lip. If we 
now look at the mouth of a flea, our 
first impression will be that none of 
the above mentioned parts are there 
