[121] See _Bd._ pl. lxii. [122] See _Bd._ vol. i. pp. 494-498, for detailed description of structure in recent and fossil Zamiæ and Cycadeæ. The existing species of Cycadaceæ are exclusively natives of hot regions, and chiefly inhabit the West Indies, South Africa, Equinoctial America, Japan, New Holland, &c.; not one species is known in Europe: a fact in striking contrast with the abundance of fossil plants of this order, which occur throughout the secondary formations of England and the continent.[123] [123] The most interesting collection of living Cycadeæ and Zamiæ near London, is that of James Yates, Esq., of Lauderdale House, Highgate; it comprises choice examples of several of the sub-genera into which these plants are now divided by botanists. No true cycads have hitherto been discovered in the carboniferous deposits; it is in the floras of the secondary epochs, from the new Red to the Cretaceous inclusive, that this tribe of plants forms an important feature. The foliage, stems, and fruits, occur in a fossil state; and as these organs cannot be referred with certainty to their respective plants, distinct genera are formed for their reception. _Foliage._--From the tough and durable nature of the leaves, the foliage of the Cycadeæ occurs in a fine state of preservation; and in the fluvio-marine deposits of the Oolite of Yorkshire, many specimens of great beauty have been collected. I know not another locality in England so rich in fossils of this kind, as the cliffs along the coast near Scarborough; Gristhorpe Bay is well known to collectors. Not only the leaves, but also the fruits or cones occur, and of these, examples are to be seen in most public museums.[124] The leaves are carbonized, but the venation is well preserved. [124] British Museum: see Petrifactions, p. 54, Room 1, Case F. [Illustration: Lign. 46. Part of a leaf of Pterophyllum comptum; _nat._ _Oolite, Scarborough._] The leaflet of the recent Cycas is distinguished by a strong nervure, which runs along the middle; that of Zamia has no midrib, but fine parallel veins that pass direct to the margin. Pterophyllum comptum. _Lign. 46._--The general aspect of these fossils is shown in this figure of a leaf, referred to the genus _Pterophyllum_, which is characterized by leaflets, often slightly united at their base, truncated at the summit, of a quadrangular or oblong form, and having fine, straight, parallel veins. The leaves are ten or twelve inches long, and have fine lanceolate leaflets; they are abundant in the same beds, and are often associated with the cones or fruit[125] figured in _Lign. 48_. [125] Brit. Mus. Petrifactions, p. 55. [Sidenote: ZAMITES PECTINATUS.]