14? On the present state of Zoology. 
ses of animals. When the question is reduced to whether two ani- 
mals belong to the same species, or whether two species can rightly 
be referred to the same genus, we can but commit an error of one or 
a few steps, which, when detected, will excite but little notice. Ne- 
vertheless, we believe that we should much lessen all chance of er- 
ror, by knowing the whole structure of the animals before us. In the 
present state of the science, it is necessary to have recourse to very 
subtle external distinctions for characterising genera and species. But 
their very subtility is an argument for enquiring as far as possible in- 
to their true value ; and it remains yet to be shewn, that there are 
not, at least in many cases, as subtle distinctions to be found inter- 
nally, with which the former are associated, and which, being known, 
tend to raise their importance. It is, then, on these grounds that we 
rejoice to see so much endeavour at the present day to elucidate the 
internal organization of animals. Much has been done in this respect 
by the Zoological Society, which affords to naturalists the double ad- 
vantage of studying the habits of those animals which it possesses 
while living, and of investigating their anatomical structure when 
dead, We need only refer to the Proceedings and Transactions of 
that scientific body, to see the advance which has been made of late 
years in this very important department of Zoology. 
But there are other grounds upon which we may take up this ar- 
gument. Comparative Anatomy is of service to the Zoologist, not 
merely for helping him to the true value of external characters, but 
in some cases for determining the actual nature of those external or- 
gans from which these characters are derived. As an instance in point 
we may refer to a remark lately made by Professor Agassiz respect- 
ing the supposed affinity of the Cyprinidce to the Siluridce. It 
would seem, says he, that " from the bearded Carps to the bearded 
Siluri there was a natural transition by means of the bearded Loaches; 
but it is important to distinguish that in these latter, as well as 
in the Carps and other Cyprinidce, the beards, as they are called, 
are merely processes of the skin ; while in the Siluri, the cirri of the 
angles of the mouth are actually prolongations of the maxillary bones 
becoming gradually cartilaginous and tapering into thread-like extre- 
mities." * This appears, then, to be a case, in which naturalists had 
supposed two external organs to be of a similar nature, which, upon 
dissection, prove different. We do not assert that the affinity be- 
tween these tribes has been grounded solely upon the presence of such 
organs : we simply inquire, whether our views are not necessarily a 
* Proceed, of Zool. Soc. 1835, p. 150. 
