With regard to the zoological affinities between the living and extinct species of testaceous Cephalopoda, Dr. Buckland remarks, "that they are all connected by one plan of organization; each forming a link in the common chain which unites the existing species with those that prevailed among the earliest conditions of life upon our globe; and all attesting the identity of the design that has effected so many similar ends, through such a variety of instruments, the principle of whose construction is, in every species, fundamentally the same.
"Throughout the various living and extinct genera of these beings, the use of the air-chambers and siphuncle of their shells, to adjust the specific gravity of the animals in rising and sinking, appears to have been identical. The addition of a new transverse plate within the coiled shell added a new air-chamber, larger than the preceding one, to counterbalance the increase of weight that attended the growth of the shell and body of these animals." (Bd. p. 380.)
The occurrence of the Nautilus, and its congeners, among the earliest traces of the animal kingdom, and their continuance throughout the immense periods during which the family of Ammonitidæ was created, flourished, and became extinct, and the existence of species of the same genus at the present time, are facts too remarkable to have escaped the notice even of those who are not professed cultivators of geological science; and I am induced to quote the following beautiful lines, by Mrs. Howitt, to impress this interesting phenomenon more strongly on the mind of the youthful reader.[428]
[428] The poetess has, however, not been literally accurate regarding the Nautilus and its habits, nor as to the formation of stratified rocks, but has given a romantic rather than a scientifically correct view of this interesting Cephalopod, and of the disappearance of its congener. The young reader must, therefore, remember that the Nautilus sometimes floats, but never sails; and that the whole race of Ammonites died out in course of time, and were not annihilated by convulsive movements of earth and sea.
"TO THE NAUTILUS.
"Thou didst laugh at sun and breeze,
In the new created seas;
Thou wast with the reptile broods
In the old sea solitudes,
Sailing in the new-made light,
With the curl’d-up Ammonite.
Thou surviv’dst the awful shock,
Which turn’d the ocean bed to rock,
And changed its myriad living swarms,
To the marble’s veined forms.
"Thou wast there, thy little boat,
Airy voyager! kept afloat,
O’er the waters wild and dismal,
O’er the yawning gulfs abysmal;
Amid wreck and overturning,
Rock-imbedding, heaving, burning,
Mid the tumult and the stir;
Thou, most ancient mariner,
In that pearly boat of thine,
Sail’dst upon the troubled brine."
ON COLLECTING FOSSIL CEPHALOPODA.