On the present state of Zoology. 3 
these organs, when considered in action and in connection with the 
living- principle. Hence it appears, that Comparative Anatomy and 
Physiology are properly subordinate departments of Zoology. Never- 
theless, from the immensity of the field which is thus let in upon our 
view, these last may almost be regarded as distinct sciences ; and the 
Zoologist be considered as restricting his enquiries more exclusively 
to the habits and classification of animals, and to those distinguishing 1 
characters by which their different relations are pointed out. Yet, 
since all natural arrangement is based upon a knowledge of the whole 
structure, he cannot safely advance on this head any further than the 
point to which that structure has been revealed by the anatomist. 
He may succeed in finding certain external signs by which it is pos- 
sible to discriminate a particular group from all others, but these signs, 
in order to be of any value, must necessarily be co-ordinate with a 
given arrangement of the internal organs, which internal organs are 
therefore assumed as known. 
It is difficult to form any adequate idea of the large number of facts, 
which it falls to the province of Zoology, even thus restricted, to re- 
cord and classify. So various are the forms assumed by different ani- 
mals ; so diversified their modes of life, their habits and economy, 
their instincts, whether exerted for the preservation of the indivi- 
dual or for the continuance of the species ; so dispersed the localities 
in which the yare found resident, the earth, the air, the ocean, 
all teeming with their respective inhabitants, and giving rise to a 
countless series of phenomena ; so complex too are the affinities by 
which they are severally related to one another ; that there seems 
hardly any limit to the enquiries which it becomes necessary to make 
in order to get acquainted with the details of their history. But our 
astonishment is excited most, by considering the immense number of 
species included in the animal kingdom, a number far exceeding that 
of plants and minerals put together. In an article in the Edinburgh 
New Philosophical Journal, published in October 1833,* the total 
number of known living species of animals, is estimated at 78,849. 
This, however, is probably far below the truth, since, according to Mr 
Macleay, upwards of 100,000 species of Annulosa alone are already 
contained in our cabinets.f What may be the entire number of spe- 
cies actually existing, in all the several classes combined, it is impos- 
sible to conjecture. Perhaps it may be thought that we are by this 
time nearly acquainted with the larger animals. But let it be remem- 
bered that a somewhat similar opinion was entertained by Ray so long 
* Vol. xv. p. 221. f Hor. Ent. part ii. p. 468. 
