eet,
the extinct Titanosaurus of the American Jurassic beds, the largest land
animal yet known to us, 100 feet in length and 30 in height; the
Whalebone Whale over 70 feet, Sibbald's Whale is said to have reached
80-90, which is perhaps the limit. Captain Scoresby indeed mentions a
Rorqual no less than 120 feet in length, but this is probably too great
an estimate.

COMPLEXITY OF ANIMAL STRUCTURE

The complexity of animal structure is even more marvellous than their
mere magnitude. A Caterpillar contains more than 2000 muscles. In our
own body are some 2,000,000 perspiration glands, communicating with the
surface by ducts having a total length of some 10 miles; while that of
the arteries, veins, and capillaries must be very great; the blood
contains millions of millions of corpuscles, each no doubt a complex
structure in itself; the rods in the retina, which are supposed to be
the ultimate recipient of light, are estimated at 30,000,000; and
Meinert has calculated that the gray matter of the brain is built up of
at least 600,000,000 cells. No verbal description, however, can do
justice to the marvellous complexity of animal structure, which the
microscope alone, and even that but faintly, can enable us to realise.

LENGTH OF LIFE

How little we yet know of the life-history of Animals is illustrated by
the vagueness of our information as to the age to which they live.
Professor Lankester[18] tells us that "the paucity and uncertainty of
observations on this class of facts is extreme." The Rabbit is said to
reach 10 years, the Dog and Sheep 10-12, the Pig 20, the Horse 30, the
Camel 100, the Elephant 200, the Greenland Whale 400 (?): among Birds,
the Parrot to attain 100 years, the Raven even more. The Atur Parrot
mentioned by Humboldt, talked, but could not be understood, because it
spoke in the language of an extinct Indian tribe. It is supposed from
their rate of growth that among Fish the Carp is said to reach 150
years; and a Pike, 19 feet long, and weighing 350 lbs., is said to have
been taken in Suabia in 1497 carrying a ring, on which was inscribed, "I
am the fish which was first of all put into the lake by the hands of the
Governor of the Universe, Frederick the Second, the 5th Oct. 1230." This
would imply an age of over 267 years. Many Reptiles are no doubt very
long-lived. A Tortoise is said to have reached 500 years. As regards the
lower animals, the greatest age on record is that of Sir J. Dalzell's