Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/373

 Rh land plants in the Secondary formations, (from the Keuper to the Chalk inclusive;) one half of these are Coniferæ and Cycadeæ, and of this half; twenty-nine are Cycadeæ; the remaining half are chiefly vascular Cryptogamiæ, viz. Ferns, Equisetaceæ, and Lycopodiaceæ. In our actual vegetation, Coniferæ and Cycadeæ scarcely compose a three hundredth part.

The family of Cycadeæ comprehends only two living Genera; viz. Cycas, (Pl. 58.) and Zamia. (Pl. 59.) There are five known living Species of Cycas and about seventeen of Zamia. Not a single species of the Cycadeæ grows at the present time in Europe; their principal localities are parts of equinoctial America, the West Indies, the Cape of Good Hope, Madagascar, India, the Molucca Islands, Japan, China, and New Holland.

Four or five genera, and twenty-nine species of Cycadeæ, occur in the fossil Flora of, the Secondary period, but remains of this family are very rare in strata of the Transition, and Tertiary series.