Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: June 13, 2025
The oldest group of plants with which we are well acquainted is that of whose remains coal is constituted; and as far as they can be identified, the carboniferous plants are ferns, or club-mosses, or Coniferae, in many cases generically identical with those now living! Among animals, instances of the same kind may be found in every sub-kingdom.
In the department of zoology, we see zoophytes, radiata, mollusca, articulata, existing for ages before there were any higher forms. The first step forward gives fishes, the humblest class of the vertebrata; and, moreover, the earliest fishes partake of the character of the next lowest sub-kingdom, the articulata.
We have now arrived at the great sub-kingdom of the Vertebrata, and will commence with the lowest class, that of fishes. Besides the claspers, the males of many rays have clusters of strong sharp spines on their heads, and several rows along "the upper outer surface of their pectoral fins." These are present in the males of some species, which have other parts of their bodies smooth.
So complete is this community of nature that for some time past many naturalists have wished to establish for these lowest types a sub-kingdom, intermediate between the animal and the vegetal: the reason against this course being, however, that the difficulty crops up afresh at any assumed places where this intermediate sub-kingdom may be supposed to join the other two.
There is no certainly known extinct order of Protozoa; there is but one among the Coelenterata that of the rugose corals; there is none among the Mollusca; there are three, the Cystidea, Blastoidea, and Edrioasterida, among the Echinoderms; and two, the Trilobita and Eurypterida, among the Crustacea; making altogether five for the great sub-kingdom of Annulosa.
The sub-kingdom Annulosa, furnishes good illustrations. Among the lower types the body consists of numerous segments that are alike in nearly every particular.
This seems a general rule in the whole class in respect to the many remarkable structural differences between the sexes. We shall hereafter find the same law prevailing throughout the great sub-kingdom of the Vertebrata; and in all cases it is eminently distinctive of characters which have been acquired through sexual selection.
On the contrary, they maintain a strict analogy throughout the whole of their subsequent courses, sub-kingdom for sub-kingdom, class for class; shewing a beautiful, though as yet obscure relation between the two grand forms of being, and consequently a unity in the laws which brought them both into existence.
But does such diversity disprove a fundamental unity? All modern science answers, No. How much of outward resemblance is there between a fish and a philosopher? Is not the difference here as wide as the widest unlikenesses in human belief? Yet Comparative Anatomy, with none to deny its right, includes philosopher and fish in one category: they both belong to the vertebrate sub-kingdom.
Now it is a most remarkable circumstance that, viewed on the great scale, living beings have differed so little throughout all geologic time that there is no sub-kingdom and no class wholly extinct or without living representatives.
Word Of The Day
Others Looking