ber and variety; and the Butterflies, Bugs, Flies, Grasshoppers,
Dragon-Flies, Beetles, etc., described in his volumes, would hardly be
distinguished from our own, except by a practised entomologist. Among
Crustacea, the Shrimp-like forms of the earlier geological epochs have
become much less conspicuous, while Crabs and Lobsters are now the
prominent representatives of the class. Among Mollusks, the Chambered
Shells, hitherto so numerous, have become, as they now are, very few in
comparison with the naked Cephalopods. The Nautili, however, resemble
those now living in the Pacific Ocean; and some fragments of the
Paper-Nautilus have been found, showing that this delicate shell was
already in existence. There is one very peculiar type of this class,
belonging to the Tertiaries, which should not be passed by unnoticed. It
partakes of the character both of the Cretaceous Belemnites and of the
living Cuttle-Fish, and is known as the Spirulirostra. Another very
characteristic group among the Tertiary Shells is that of the
Nummulites, formerly placed by naturalists in immediate proximity with
the Ammonites, on account of their internal partitions. This is now
admitted to have been an error; their position is not yet fully
determined, but they certainly stand very low in the scale, and have no
affinity whatever with the Cephalopods. The subjoined wood-cut
represents one of these Shells, so numerous in the Tertiaries that large
masses of rock consist of their remains. The Univalve Shells or
Gasteropods of the Tertiaries embraced all the families now living,
including land and fresh-water Shells as well as the marine
representatives of the type. Some of the latter, as, for instance, the
Cerithium, are accumulated in vast numbers. The limestone quarries out
of which Paris is chiefly built consist wholly of these Shells. The
fresh-water basins were filled with Helices, one of which is represented
in the following wood-cut, with Planorbis, Limnaeus and other Shells
resembling those now so common in all our lakes and rivers, and
differing from the living ones only by slight specific characters. The
Bivalves also have the same resemblance to the present ones, including
fresh-water Mussels as well as the marine Clams and Oysters. Among
Radiates, the higher Echini (Sea-Urchins) have become numerous, while
the other Echinoderms of all families abound. Corals include, for the
first time, the more highly organized Madrepores.

[Illustrati