But, if the Pearly Nautilus is the inferior and poor relation of the argonaut, it lives in a handsome house, and comes of an ancient lineage. The Ammonites, whose beautiful whorled and chambered shells, and the casts of them, are so abundant in every stratum, especially in the lias, the chalk, and the oolite, had four gills also. These Ammonites and the Nautili were amongst the earliest occupants of the ancient deep; and, with the Hamites, Turrilites, and others, lived upon our earth during a great portion of the incalculable period which has elapsed since it became fitted for animal existence, and in their time witnessed the rise and fall of many an animal dynasty. But they are gone now; and only the fossil relics of more than two thousand species (of which 188 were Nautili) remain to tell how important a race they were amongst the inhabitants of the old world seas. They and their congeners of the chambered shells, however, left one representative which has lived on through all the changes that have taken place on the surface of this globe since they became extinct--namely, _Nautilus pompilius_, the Nautilus of the pearly shell--the last of the Tetrabranchs. I need offer no apology for endeavouring to explain the difference between the Nautilus of the chambered shell and the argonaut with the membranous arms which it was supposed to use as sails, when Webster, in his great standard dictionary, describes the one and figures the other as one and the same animal; and when a writer of the celebrity of Dr. Oliver Wendell Holmes also blends the two in the following poem, containing a sentiment as exquisite as its science is erroneous. I hope the latter distinguished and accomplished author, whose delightful writings I enjoy and highly appreciate, will pardon my criticism. I admit that the beauty of the thought might well atone for its inaccuracy, (of which the author is conscious,) were it not that the latter is made so attractive that truth appears harsh in disturbing it. "THE CHAMBERED NAUTILUS." "This is the ship of pearl, which poets feign Sails the unshadowed main, The venturous bark that flings On the sweet summer wind its purpled wings, In gulfs enchanted, where the siren sings, And coral reefs lie bare, Where the cold sea-maids rise to sun their streaming hair. Its webs of living gauze no more unfurl, Wrecked is the ship of pearl! And every chambered cell, Where its dim, dreaming life was wont to dwell, As the frail tenant shaped his growing shell, Before thee lies revealed, Its irised ceiling rent, its sunless crypt unsealed!