Page images

numerous in this our island, although it is still as true as it was in the time of Trinculo, that if a strange beast' be exhibited here, • there is not a holyday fool but would give a piece of silver.' Whether it be a giant or a dwarf, a natural or artificial deformity, a Chinese mermaid, or any creature born with more or less than its due proportion of members, it will not want admirers of a certain class. “But there is also no country where so many persons can be found of inquiring mind and liberal education, and yet almost entirely ignorant even of the first elementary steps of natural history. If these are without skill in comparative anatomy, and are yet interested in the results of these osteological researches, we may remind them that a leaning on the side of credulity was deemed truly philosophical by Pliny-nam mihi contuenti se persuasit Rerum Natura nihil incredibile existimare de eâ.'* · If any thing could justify,' says Cuvier,' those hydras and other monsters whose figures are so often repeated in the monuments of the middle ages, it would incontestably be the Plesiosaurus.'+ Yet we may confidently say of this creature, and of the Megalosaurus and Iguanodon, what Ariosto had the audacity to declare of his hyppo-griffin :

• Non finzion d'incanto come il resto

Ma vero e natural si vedea questo.' The Pterodactyls, however, or flying lizards, described by Cuvier,f recal still more forcibly to our recollection the winged dragons of fabulous legends. They might, perhaps, have been as inoffensive as the small flying reptile now found in Asia and Africa ;but the size of some of them, their long jaws armed with sharp teeth, and the hooked nails of their claws, would render them truly terrific were they to revisit Christendom, now no longer under the shield of the Seven Champions. That we should find some fictitious animals of romance nearly realized, upon being suddenly admitted as it were to the creations of new worlds, will surprize none who are conversant with the laws of organic nature, and who have well considered the principles on which the charms of poetic fiction depend. In fabricating ima. ginary animals the license of fiction does not extend to extravagant violations of known analogies, but merely to the combination of parts and functions never yet seen to co-exist. It is not long since naturalists discovered in a living animal, the Ornithorhynchus of New Holland, the organization and habits not


Pliny, lib. xi. chap. 3.
+ Cuvier, Discours sur les Rev. p. 303. 1825.

Cuv. Oss. Fos. vol. ii. part ii. p. 358. 380.
Draco volans Linn. See Shaw, vol. iii. p. 177.


only of different genera, but of three distinct classes of former systems, all united and blended together in one single individual:

To enter at large into the consideration of other classes of organic remains, or to examine in detail those described in the present volume, would be inconsistent with our present limits and scope. In the illustration of these objects, lithography has been successfully employed. This art, so strongly recommended by its surior cheapness, may exert a favourable influence on the future progress of science, and particularly on natural history, which has always been retarded by the unavoidable expense of engraving. The plates descriptive of the osteological structure of the large Reptiles we have been mentioning deserve especial commendation, as do the figures of plants discovered by Mr. Mantell in the same strata with the Iguanodon, near Cuckfield in Susses. These remains consist partly of ferns, that numerous fossil genus, and partly of vegetables analogous to the genera Zamia and Cycas, now particularly characteristic of tropical regions. The plates of Orthoceræ* from the islands of Lake Huron are also admirably executed in lithography. These chambered univalve shells, so interesting to the conchologist from the peculiar structure of the siphuncle, are described in a paper by Dr. Bigsby on the geology of part of North America bordering on Lake Huron. No recent species of Orthocera hitherto discovered exceeds half an inch in length; the fossil species both in Europe and America frequently attain the length of many feet. The only multilocular univalve Testacea of large dimensicus now existing are some species of Nautilus, and these are confined to tropical climates. The abundance therefore of Ammonites, Orthoceræ, and Nautili of great magnitude, in the strata of Europe and North America, is worthy of observation, as tending, in concurrence with other branches of organic remains, to confirm that striking deduction of geology, that the former temperature of the northern hemisphere was much higher than it is at present.

As the fossil species appear to be all, with very few exceptions, extinct, we reason only from analogy when we draw this conclusion, and we ought therefore to require a great accumulation of evidence, together with perfect harmony in the proofs. This question, concerning the former temperature of the globe, is extremely interesting, and it has so often been alluded to during our consideration of fossil animals and plants, that we shall lay before

* However great may be the expedience of a speedy reform in the nomenclature of natural history, we must not attempt it in this place. It may be as well, in compassion to the uninitiateri, to inform them that, when Lamarck writes Orihocera, he means Orthoceras, and that, iu tire language now spoken by conchologists, Orthocera stands for Orthocerata.


our readers a concise view of the principal data on which the prevailing opinions of naturalists in regard to it are founded.

Remains of large herbivorous quadrupeds occur in the superficial gravel of Europe and North America, referable to genera now contined to warmer climates. Their number does not diminish as we proceed northwards, but, on the contrary, the greatest abundance has been found in Siberia, where the vegetation is now so scanty and buried for so long a time under the snow of a polar winter, that it is impossible to conceive how herds of elephants could ever have existed there, had the climate been always so severe as it is at present. Various oviparous quadrupeds, tortoises, turtles, crocodiles, and those gigantic Saurian animals, which engaged our attention in an earlier part of this essay, are distributed in profusion throughout the strata of every part of Europe, some even in the most recent formations above the chalk, and others in different parts of the series, down to the lias and the copper-slate of Thuringia inclusive. Nothing analogous to these classes of large reptiles exists at present in tenperate latitudes.

Univalve shells are said to predominate in number over bivalves throughout the secondary strata in Europe, as at present in tropical seas.* To the occurrence of large chambered univalve shells, and the conclusions to which they point, we need not again refer. Corals and other zoophytes are found at present to increase in size, in variety of species, and rapidity of growth, as we approach the equator. They form large reefs in intertropical seas, where their comminuted fragments constitute a considerable portion of the beach, and are remarkable for their tendency to consolidate, with other loose materials, into rock. Such a state of things must be supposed to have existed when the oolitic series and many other strata in Europe were deposited. But as we ascend towards the superior and more recent formations, which contain genera of shells more analogous to those now inhabiting our seas, fossil zoophytes become much rarer and inferior in size.

The above inferences are derived from so extensive a collection of facts, that the number of exceptions must be regarded as singularly small, and most of these are merely founded on analogy Jike the evidence on the other side. Remains of Cetaceous animals, for example, of a genus now exclusively tropical, have been discovered in a limestone in France, the calcaire grossière, with a species of another Cetaceous genus now peculiar to the frozen zone.t. A more remarkable exception occurs in the discovery of

* Defrance, Tab. des Corps Org. Foss. 51. 125. + Cuv. Discours sur les Rev. p. 313.


bones of a deer (not distinguishable from a rein-deer, a species now confined to frozen latitudes) with those of the Rhinoceros and other fossil quadrupeds of the same epoch.* They, however, belong to superficial gravel, and it is not pretended that the organic remains of this debris afford such strong indications of a tropical temperature as older formations; besides that it is impossible to affirin that animals thus confusedly mixed together were in every instance contemporaneous, or were not buried in the gravel at distinct and distant periods. That genera of animals now exclusively tropical may once have contained species adapted to live in colder climates is undeniable. We find existing species, for instance, of the Ox kind, universally distributed; the musk ox in the arctic, the common ox in the temperate, and the buffalo in the equatorial regions. But notwithstanding these and other objections, the argument from analogy is unimpaired, so long as it is incontestably established that certain families or groups of genera of animals are at present characteristic of warmer climates, and are wanting, or but feebly represented, in colder latitudes : the same law holding equally with regard to assemblages of fossil remains, and most unequivocally so in some formations of considerable antiquity.

Although our knowledge of fossil Plants is more limited, they supply proofs, still more decided than do animal remains, of the ancient high temperature of the earth. The vegetation of tropical countries is now distinguished from that of colder latitudes by the luxuriance and predominance of the Palm tribe, by the arborescence of Ferns and certain kinds of Grasses, and many other characters; but several


of plants are at present common to arctic, temperate, and equinoctial climates. Now, as we descend to ancient strata, particularly the coal, plants belonging to families and genera analogous to Palms, abound, together with Tree-ferns of great size, and Grasses arborescent on a scale of magnitude never obtained at present even between the tropics; while those genera and families now characteristic of cold climates, or even such as are common both to temperate and tropical regions, are entirely absent. The only approach yet discovered in the organization of any coal-fossils to plants now abounding in temperatę climates is to be found in those supposed by some writers to have formed a link between the Palmaceous and Coniferous orders; but even these latter, it will be remembered, are not excluded at present from tropical countries. Hence the most eminent botan ists who have yet directed their attention to this study have been led to infer that, when the coal-plants were in existence, the heat

* Cuv. Discours sur les Rev. p. 342, 1825.


was far more intense than is now experienced even between the tropics; and however astonishing this inference may seem, it can scarcely be rejected until some ground is shown for distrusting all evidence derived from analogy on these subjects. That we by no means comprehend all the laws that regulate the geographical distribution of living plants over the globe must be confessed. That there are some causes hitherto undiscovered, capable, in co-operation with temperature, of promoting or retarding the development of certain forms and characters of vegetation, is more than probable; but that temperature is at present the most powerful of all, is unquestionable; and that it was so when the Plants of the coal were in being we must presume, until reasons are adduced for believing that the system of nature has, in this respect, been entirely changed.

As to the manner in which so surprizing a revolution in the temperature of the globe has been effected, no conjecture deserving much consideration has yet been made known; and if a satisfactory explanation of so difficult a problem is ever obtained, we shall probably be indebted to astronomy for it. Geology can only account for local fluctuations of climate in the same latitudes, by furnishing us with evidence almost conclusive, that; during the deposition of stratified rocks, changes in the distribution of land and sea were frequent and considerable. In consequence of these changes the relative extent of superficial land and


often have differed greatly. Continents or open seas may have alternately existed at the poles or at the equator. The land, according to its varying form, would necessarily determine in particular directions warm currents from tropical towards arctic seas, or cold currents bearing floating ice from arctic towards tropical latitudes. But these causes, though far too important to be kept out of view whenever this question is considered, are essentially partial in their operation and limited in degree; whereas the phenomena indicate most signal and remarkable alteration in climate, and that co-extensive with every part of the northern hemisphere hitherto examined in America, Europe, and Asia.

Some modern authors conceive that a comparison of the fossils of Bengal, the Carnatic and other equatorial countries, with those of Europe and North America, warrants the conclusion that the former temperature of the earth was more uniform as well as more elevated than the present; and they endeavour to explain this circumstance by supposing that climate was formerly independent, in a great degree, of solar heat, deriving warmth from the interior of the earth itself, which, since the original oxydation of its metallic nucleus, has been (say they) in a state of gradual refrigeration. We should not have ventured to amuse our readers


« PreviousContinue »