Page:A Treatise on Geology, volume 1.djvu/238

which has been ascribed to the deposition of formations, from considerations founded merely on the state of conservation of organic remains.

Organic Remains.—The numerous remains of plants, zoophyta, mollusca, articulosa, and vertebral animals, belonging to the oolitic system, have long been celebrated and represented in many works of merit in England and Germany. Some general considerations arise from a contemplation of them, which deserve attention. The following estimate of the numbers of specific forms in the whole system (exclusive of the wealden formations), drawn up by the author, is at this time undoubtedly below the truth. (Encycl. Metrop. p. 653.)

Plants —	marine		4	— In limestone chiefly
	terrestrial cryptogamous		39	$\left\{{\begin{matrix}\ \\\\\ \end{matrix}}\right.$	In sandstones and shales chiefly.
	monocotyledonous		33
	gymnospermous	$\left.{\begin{matrix}\ \ \end{matrix}}\right\}$	4
	uncertain
Polyparia —	fibrous		75	$\left\{{\begin{matrix}\ \\\\\ \end{matrix}}\right.$	Chiefly in limestones, but rarely in the lias.
	corticiferous and celluliferous	$\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}$	44
	lamelliferous		59
Kadiaria —	crinoidea		31
	stellerida		17
	echinida		47		Chiefly in limestone, rarely in lias.
Conchifera —	plagimyona		189
	mesomyona		134
	brachiopoda		61
Mollusca —	gasteropoda		114
	cephalopoda		273
	annulosa		55
	Crustacea		22	— Chiefly astacidæ
	insects		20	— Solenhofen and Stonesfield.
	fishes		20
	reptiles		40
	mammalia		2 or 3		Only in the lower oolite formation at Stonesfield.

In the wealden formation, are no zoophyta, no cephalopoda—various land plants—some fresh-water bivalves and univalves—a few estuary shells—cyprides, lepidotus, and other fishes—iguanodon, hylsæosaurus plesiosaurus, &c., with various chelonida, both of fresh and salt water.

The most characteristic of the plants are the group of cycadeæ, of which stems in the isle of Portland, and leaves and fruits in Yorkshire, show considerable analogy to the existing forms of the tribe, at the Cape of Good Hope, and in India and Australia. Compared with