these forms were first recognised by the writer in the bituminous shale of Kettle Point, Lake Huron. [Illustration: FIG. 92.—A Devonian Taxine Conifer (_Dadoxylon ouangondianum_, Dn.). St. John, New Brunswick. A, Fragment showing _Sternbergia_ pith and wood; _a_, Medullary sheath; _b_, Pith; _c_, Wood; _d_, Section of pith. B, Wood cell _a_, and hexagonal areole and pore _b_. C, Longitudinal section of wood, showing _a_, Areolation, and _b_, Medullary rays. D, Transverse section showing _a_, Wood-cells, and _b_, Limit of layer of growth.] [Illustration: FIG. 93.—Group of Devonian Fruits, &c. Middle Devonian, New Brunswick. A, _Cardiocarpum cornutum_. B, _Cardiocarpum acutum_. C, _Cardiocarpum Crampii_. D, _Cardiocarpum Baileyi_. E, _Trigonocarpum racemosum_. E¹, E², Fruits enlarged. F, _Antholithes Devonicus_. F¹, Fruit of the same. G, _Annularia acuminata_. H, _Asterophyllites acicularis_. H¹, Leaf. K, _Cardiocarpum_. (? young of A.) L, _Pinnularia dispalans_. From _Acadian Geology_. ] [Illustration: FIG. 94.—Structures of the oldest-known Angiospermous Exogen (_Syringoxylon mirabile_, Dn.). From Eighteen-mile Creek, Lake Erie. 1, Transverse section x 100. 2 and 3, Portions of the same x 300. 4, Longitudinal section x 300. 5, Fragment of duct from the same x 600. 6, Wood cells and medullary ray x 600.] The Devonian flora seems to have been introduced in the northern parts of the American continent at a time of warm and equable climate, and of elevation of new land out of the Silurian sea. It spread itself to the southward, and was finally destroyed in the great subsidences and disturbances which closed the Devonian age, and which were probably accompanied with refrigeration of climate. It was succeeded by the more massive and richer, but more monotonous flora of the Carboniferous, a period in which large areas of our continents were in the state of swampy and often submerged flats, and in which the climate was again warm and uniform. [Illustration: FIG. 95.—_Asterophyllites parvula_ (Dn.), and _Sphenophyllum antiquum_ (Dn.). Middle Devonian, New Brunswick.] The Carboniferous age was, even more emphatically than the Devonian, an age of Acrogens and Conifers. A few Carboniferous Fungi have recently been discovered, but there are no known Lichens or Mosses. There seem to be a few Endogens, but no true Exogens. The great bulk of the plants consists of Acrogens and Gymnosperms, as in the previous period. As this flora is so very important and so much better known than any other of those belonging to the infancy of the vegetable kingdom, we may notice a little in detail some of its leading forms. [Illustration: FIG. 96.—_Calamites._ Carboniferous. A, _C. Suckovii_. B, _C. Cistii_ (Bt.). C, Base of _Calamites_. D, E, Structures. From _Acadian Geology_.] [Illustration: FIG. 97.—Carboniferous Ferns.