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The closely allied species also of the larger genera apparently have restricted ranges, and they are clustered in little groups round other species in which respects they resemble varieties. These are strange relations on the view of each species having been independently created, but are intelligible if all species first existed as varieties.
But if, somewhere in that vast hall, there were a few preparations, exemplifying the leading structural peculiarities and the mode of development of a common fowl; if the types of the genera, the leading modifications in the skeleton, in the plumage at various ages, in the mode of nidification, and the like, among birds, were displayed; and if the other specimens were put away in a place where the men of science, to whom they are alone useful, could have free access to them, I can conceive that this collection might become a great instrument of scientific education.
It is, of course, impossible to say with certainty through which of the three-toed genera of the pliocene that lived together the succession came. It is not impossible that the latter species, which appear generically identical, are the descendants of more distinct pliocene types, as the persistent tendency in all the earlier forms was in the same direction.
In certain genera of star-fishes, "the very combinations needed to show that the pedicellariae are only modified branching spines" may be found. Thus we have fixed spines, with three equi-distant, serrated, movable branches, articulated to near their bases; and higher up, on the same spine, three other movable branches.
Both the male and female gallitos are of an olive-brown; but the pollo, or young male, is distinguishable at the earliest age, by its size and its yellow feet. This tint grows pale more easy than in the other genera of the passerine order. The young males, as in most other birds, have the plumage or livery of their mother.
I could see, without great effort of the imagination, the shoal of Lockport teeming with the many genera of crinoids which the geologists of New York have rescued from that prolific Silurian deposit, or recall the formations of my native country, in the hill-sides of which also, among fossils indicating shoal water deposits, other crinoids abound, resembling still more closely those we find in these waters.
On this idea of the natural system being, in so far as it has been perfected, genealogical in its arrangement, with the grades of difference expressed by the terms genera, families, orders, etc., we can understand the rules which we are compelled to follow in our classification.
In some other genera they are present, but in a rudimentary condition. In the Ateuchus or sacred beetle of the Egyptians, they are totally deficient.
From the stove opens a very long, narrow house, where cool genera are "plumping," laid out on moss and potsherds; many of them have burst into strong growth. Pleiones are flowering freely as they lie. This farmer's crops come to harvest faster than he can attend to them.
He is confident that intermediate forms must have existed; that in the olden times when the genera, the families, and the orders, diverged from their parent stocks, gradations existed as fine as those which now connect closely related species with varieties. But they have passed and left no sign.
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