t prolific vegetable growth.
* * * Whether the vegetation of the Laurentian was wholly aquatic or in
part terrestrial we have no means of knowing." In 1855, Dr. T. Sterry
Hunt asserted "that the presence of iron ores, not less than that of
graphite, points to the existence of organic life even during the
Laurentian or so-called Azoic period." In 1861 he went farther and
stated his belief in "the existence of an abundant vegetation during the
Laurentian period." The Eophyton in Labrador occurs above the Trilobite
(Paradoxides) beds, while in Sweden they occur below.]

[Footnote 21: In a communication made to the Boston Society of Natural
History, Oct. 17, 1870 (see also "American Naturalist" for Feb. and
Sept., 1871).]

[Footnote 22: On the Origin of Insects, a paper read before the Linnaean
Society of London Nov. 2, 1871, and reported in abstract in "Nature,"
Nov. 9, 1871.]

[Footnote 23: This reminds us (though Ganin does not mention it) of the
development of the embryo of Julus, the Thousand legs, which, according
to Newport, hatches the 25th day after the egg is laid. At this period
the embryo is partially organized, having faint traces of segments, and
is still enveloped in its embryonal membranes and retains its connection
with the shell. In this condition it remains for seventeen days, when it
throws off its embryonal membrane, and becomes detached from the shell.]

[Footnote 24: It is a suggestive fact that these deciduous forms give
way through histolysis to true larval forms, just as in some flies
(Musca vomitoria) the true larval form goes under, and the adult form is
built up from the imaginal disks of the larva. In an analogous manner
the deciduous, pluteus-condition of the young Echinoderm perishes and is
absorbed by the growing body of the permanent adult stage. This
deciduous stage of the ichneumon may accordingly be termed the prelarval
stage. Now as we find insects with and without this prelarval stage, and
in the radiates quite different degrees of metamorphoses, the inquiry
arises how far these differences are correlated with, and consequently
dependent upon, the physical surroundings of these animals in the free
swimming condition. Merely to point out the differences in the mode of
development of animals is an interesting matter, and one could do worse
things, but the philosophical naturalist cannot rest here. He must seek
how these differences were brought about.]

[Footnote 25: Leuckart, in hi