OCR Text |
Show 4S ERA OF ,THE CARBONIFEROUS :JORMA1.JO!'C {his era, and are only as yet found in isolated cases, anti in sandstone beds. The first discovered lay in the Craigleith quarry, near Edinburgh, and consisted of a stem about two feet thick, and forty-seven feet in length. Others have since been found, both in the sanle situation and at Newcastle. Leaves and fruit being wanting, an ingenious 1node of detecting the nature of these trees was hit upon by Mr. Witham, of Lartington. Taking thin polished cross slices of the stem, and subjecting them to the microscope, he detected the structure of the wood to be that of a cone-bearing tree, by the presence of certain "reticulations" which distinguish that family, in addition to the usual radiating and concentric lines. That particular tree was concluded to be an araucaria, a species now found in Nor folk Island, in the South Sea, and in a few other remote situations. The coniferre of this era form the dawn of dicotyledonous trees, of which they may be said to be the simplest type~ and to which, it has already been noticed, the lepidoden<lra are a link from the monocotyledons. The concentric rings of the Craigleith and other coniferre of this era have been mentioned. It is interesting to find in these a record of the changing sea· sons of those early ages, when.as yet there were no human beings to observe time or tide. They are clearly traced; but it is observed that they are more slightly marked than is the case with their family at the present day, as if the changes of temperature had been within a narrower range. Such was the vegetation of the carbonigenous era, com-posed of forms at the bottom of the botanical scale, flow ·,rless, fruitless, but luxuriant and abundant beyond what a.he most favored spots on earth can now show. The rigidity of the leaves of its plants, and the absence of fleshy fruits and farinaceous seeds, unfitted it to afford nutriment to animals; and, monotonous in its forms, and destitute of brilliant coloring, its sward probably unenlivened by any of the smaller flowering herbs, its shades uncheered by the hum of insects, or the music of birds, it must ha~e beP.n but a sombre scene to a human visitant. But neither man nor any other animals were then in exis~ence to look for such uses or such beauties in this vegctatLOn .. It was ~erving other and equally important. ends, cle3:nng {probably) the atmosphere of matter noxious to _animal life, and storing up mineral masses which were In long COMM~NCEMENT 0~ LAND PLANTS. 49 subsequent ages to prove of the greatest service to the hn~an. r.a?e, ~~;en to the extent of favorino- the procrress of Its CIVIltzation. w o The ~nimal. remains of this eta are not numerous in comparison w1th those which go before, or those wh'ich Come after. The mountain limestone indeed deposited a~ t~e corn1n:encement of it, abounds ~nu ually in polypial'la and crinoidea; but when we ascend to the coal-beds tftemselves, .the case is altered, and these marine remains a ogether d1_sappear. We have then only a limited vari~~~ ~f co~chifer and shell mollusks, with fraO'ments of a . £h pec1es of fishes, a_nd these are rarely or ne·;er found ~n " e eta~ seams, but 1n the shales alternatin(J" with them t orne o t e fishes are of~ sauroio character,0that is, ar~ ake of the nat~re of the lizard, a genus of the re Jtilta !fnd class of anunals, so that we may be said here rto h;v: tJ~~ ~~st app~·o~ch to a kin~ of animals calculated to breathe found ~br et;:bb Such Is t~e .IYf~galichthys Hibbertii, wat . . . . 1 ert Ware, In a limestone bed of fresh- Edi~~u~~~~n, 3~~~~n~;~~pt~e co 1 al. adt 1 Burdiehouse, near the 1 . · • ~ .arne nn lave been found in at M~r~cl~:::~~le;;l~isYtrkslure, and in t~e low coal shales as collections ~f fresh wsa~e~· r~~rc th~~ ~Ight b~ ~xpected. mabie that they would be peop~dexisT1 ' ah? }t Ish presu .. es of the coal era are named 1 . . . 1e c lC ot er fish-diperdus. pa reothn:Ssum, palreoniscus, Coal strata are nearly fi d cnrboniferous formation co~r1~.c ~o Jhe group termed the afterwards but they occt. . 1 In e s arc not unknown thl:?'rcfore thouD'ht that tl~ n on I. as a rare exception. It is which allowed of so ab e mos unporta~t of the conditions ceased about the time unndan\t ~errestrla~ vegetation, had The ?igh temperature_,lv~s en Is formatiOn .":as closed. terminated, for there ar n.~ one of th~ conditions whic~ probably the superabundea~~~ etce.s of.It a[lerwards; but to have existed during th. ~ cal bonlc acid gas supposed close. There can be littl~s ~I a b was expend~d before its 1arg;e dose of this gas into theo~t t t~lat the mfusion of a day ~;vnuld be attended b . m_osphere at the present stances as in the tim 1 tbiCCiscly ~he same circntnLand animal life WOLlJde o t l e carboniferous formation t at I' on would be enormouIs!.O ladv e a 1p l ace on earth ; vege-. ed from the vast accurnuiat~~n coa~ strata would be forrn- 5 s ot ·woody matter, 'vhicb |