To return to the northern hemisphere, it is clear that the Wealden flora, as represented by plants recorded from England, France, Belgium, Portugal, Russia, Germany and other European regions, as also from Japan and elsewhere, carries on, with minor differences, the facies of the older Jurassic floras.
Finally, it is important to remember that the fundamental characteristic of a living organism is its power of response to environment, a response or series of responses being necessary in a continuous environment for the normal facies of the organism to appear, and necessary in a shifting environment if the organism is to change suitably and not to perish.
Has been brought about rather by extermination than specialization, and their distinctive facies by the development and multiplication of the surviving types.
They form, in fact, a special facies which may frequently be traced laterally into the more normal marine deposit of the same age.
As a rule the general facies as well as dimensions are remarkably uniform throughout a family, so that tropical species -often differ little in appearance from those inhabiting temperate regions.
The generic characters are based upon definite modifications of form which affect the entire facies of the animals, while the specific diagnoses depend upon minor characters, such as the number of myotomes or muscle-segments.
The marine facies of the later Tertiaries is confined to the neighbourhood of the coast, and was probably formed after the elevation of the Andes; but inland, freshwater deposits of this period are met with, especially in Patagonia.
A few Devonian forms have also been recorded from the Parry Archipelago, and Nathorst has shown the existence of Old Red Sandstone facies of Devonian in Traill Island, Geographical Society Island, Ymer Island and Gauss Peninsula.
As limits; but in none of these schemes has the coast of Antarctica been adequately considered, and they have all been too much influenced by the Mercator map. Each of the three oceans, Atlantic, Indian and Pacific, possesses an Antarctic facies in the southern part and a tropical facies between the tropics, and the Atlantic and Pacific an Arctic facies in their northern parts.
The, fferent facies are possibly related to slight differences in a merally uniform habitat: it is unscientific to regard them as se to chance; still, in the majority of cases, the causes of the iferent facies have not been demonstrated.