4 ^ On the present state of Zoology. 
back as in 1690. The number of known and described species of 
Beasts, under which term Serpents also were included, was estimated 
by that naturalist as not above 150 ; and he added his belief that " not 
many of any considerable big-ness, in the known regions of the world, 
had escaped the cognizance of the curious." The number of Birds 
known and described he considered as nearly 500 ; and the number of 
Fishes the same ; and he supposed that " the whole sum of beasts and 
birds might exceed by a third part, and fishes by one-half, those 
known."* Now what has been the result of discovery since then 
with respect to these groups only ? The number of Mammalia has 
been raised from 150 to 1200,-j- the number of Birds from 500 to 
6500;J: ; the number of Reptiles, included by Ray amongst his Beasts, 
has reached to 1500 ; the number of Fish, which he considered the 
same as that of birds, to 8000. || But, however large may be the pro- 
portion of known to unknown species amongst the vertebrate animals, 
that proportion must be very different, and in all probability quite in- 
significant, in the case of the invertebrate. After all one thing is cer- 
tain ; that our lists have, from the earliest times, been gradually ex- 
tending, in proportion to the increased attention which has been paid 
to the science; and judging from the immense accessions which they 
have received during the last fifty years, it is clear that if they conti- 
nue long to augment in the same ratio, we must be yet at a great dis- 
tance from the knowledge of the entire number. It may be safely as- 
serted that the number of species left recorded by Linnaeus in the 
twelfth edition of the Systema Naturae, the date of which is yet up- 
wards of seventy years posterior to that of Ray's work on the Crea- 
tion, is certainly not one-twentieth part of those we are now acquaint- 
ed with. 
With this immense assemblage of beings, and with all their several 
peculiarities of character and economy, the Zoologist has to treat. 
Every part of their history calls for his investigation. He must search 
them out in their native haunts and recesses ; follow them through 
the several stages of their existence ; observe their habits ; trace 
the different degrees of resemblance between different species ; and, 
lastly, from the facts thus accumulated, endeavour to ascend to the 
knowledge of those general laws upon which depend their affinities 
and natural classification. Well might Ray exclaim, with reference 
Wisdom of God manifested in the Works of the Creation. Sixth Edition, 
p. 21. 
f L'Institut, 1834, p. 138. 
\ Edinb. New Phil. Journ. Vol. xv. p. 223. Ibid. 
|| Agassiz, Rapport sur les Poissons Fossiles, &c. p. 57. 
