i879-] 
in the Organic World; 
43 
Madagascar. By way of contrast we may point to the 
humming-birds, perhaps the most truly aerial of vertebrates, 
some of which do not exceed 20 grains in weight, and which, 
except when sleeping or engaged in the act of incubation, 
are ever on the wing. 
The largest and heaviest inserts, — such as Goliathus 
Drurei , Dynastes elephas, &c., — though possessing organs of 
flight, use them rarely and clumsily, and may in this respect 
be instinctively contrasted with many species of tiny Diptera 
and Hymenoptera which spend nearly the whole of their 
adult stage in the air. 
An examination of the respective sizes of the various 
animal groups fully supports, therefore, the assumption with 
which I started. There are, indeed, multitudes of tiny and 
even microscopic creatures inhabiting both the salt and the 
fresh waters. But the largest species, whether still living 
or extinCt, are strictly aquatic. 
The vegetable kingdom in its turn presents us with very 
similar phenomena. The dryland, indeed, produces mighty 
plants like the Sequoia of California, the Boababof Senegal, 
and the Jarra-jarra and the gum-trees of Australia. But 
according to Prof. Reinsch, the Macrocystis pyrifera , a sea- 
plant found in the North Pacific, surpasses them all. A 
single specimen of this plant has been found, by aCtual 
measurement, to cover three square miles. 
The size of extinCt organisms, as compared with that of 
species still surviving, has often attracted attention. Here 
there certainly exists, in the popular views, a very con- 
siderable amount of exaggeration. Ever since it was placed 
beyond doubt that fossils were truly the remains of plants 
and animals which once inhabited this earth of ours, and 
not mere lusus nature or superhuman forgeries — we can 
find no better name — created specially for man’s delusion, 
it has been customary to invest the faunse of bygone geolo- 
gical epochs with a magnitude most portentous. But, as is 
the case with recent forms of life, this gigantic character 
shrinks when the test of careful measurement is applied. 
We may safely say that no fossil serpent, saurian, fish, or 
whale of one hundred yards in length has yet been dis- 
covered ; that no strata have yet disclosed the remains of a 
terrestrial carnivore of double the size of the royal tiger, or 
of a proboscidean, ruminant, edentate, or marsupial of more 
than thirty feet from head to tail. It has even been ques- 
tioned whether the mean stature of the animal kingdom has 
greatly decreased. Still we have good evidence for con- 
cluding that in almost every group species have once existed 
