explained, has been fully adopted by Sir E. Home:--"if," says the
enthusiastic baronet, "I shall prove that this, the richest jewel in a
monarch's crown, which cannot be imitated by any art of man, either in
the beauty of its form or the brilliancy and lustre produced by a
central illuminated cell, is the abortive egg of an oyster enveloped
in its own nacre, of which it receives annually a layer of increase
during the life of the animal, who will not be struck with wonder and
astonishment?" And, we must add, that the proofs are very much in
favour of this conclusion.

[12] The writer of An Introduction to the Natural History of
Molluscous Animals, in a Series of Letters: one of the
most delightful contributions to the _Magazine of Natural
History_, since the establishment of that valuable
journal.

* * * * *



ROMAN TOMBS.


"Tombs," observes the clever author of _Rome in the Nineteenth
Century_, "formed a far more prominent feature in ancient communities
than in ours. They were not crowded into obscure churchyards, or
hidden in invisible vaults, but were sedulously spread abroad in the
most conspicuous places, and by the sides of the public ways." Hence
we may add, the "_Siste Viator_" (traveller, stop!) so common upon
tombs to this day. But why are not tombs placed by the roadside in our