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But in each of our new species, the embryonic fore-limbs will differ greatly from the fore-limbs in the mature animal; the limbs in the latter having undergone much modification at a rather late period of life, and having thus been converted into hands, or paddles, or wings.
The fore-limbs, for instance, which once served as legs to a remote progenitor, may have become, through a long course of modification, adapted in one descendant to act as hands, in another as paddles, in another as wings; but on the above two principles the fore-limbs will not have been much modified in the embryos of these several forms; although in each form the fore-limb will differ greatly in the adult state.
I cannot here resist the temptation to notice one of those small points in which the accuracy of the Bible is so constantly brought to light. The popular notion of angels gives them wings as well as hands a form quite impossible from the natural history point of view; all animals of the vertebrate orders never have more than two pairs of limbs. And in winged animals the fore-limbs become wings.
But let a victim come within reach, and the attitude of prayer is promptly abandoned. Suddenly unfolded, the three long joints of the deadly fore-limbs shoot out their terminal talons, which strike the victim and drag it backwards between the two saw-blades of the thighs.
But in each individual new species, the embryonic fore-limbs will differ greatly from the fore-limbs in the mature animal; the limbs in the latter having undergone much modification at a rather late period of life, and having thus been converted into hands, or paddles, or wings.
Thanks to a flexible neck, set freely upon the thorax, the head can turn to right or left as on a pivot, bow, or raise itself high in the air. Alone among insects, the Mantis is able to direct its gaze; it inspects and examines; it has almost a physiognomy. There is a very great contrast between the body as a whole, which has a perfectly peaceable aspect, and the murderous fore-limbs.
One is reminded of the puffing of a startled adder. Proudly straddling on its four hind-claws, the insect holds its long body almost vertical. The murderous fore-limbs, at first folded and pressed against one another on the thorax, open to their full extent, forming a cross with the body, and exhibiting the axillæ ornamented with rows of pearls, and a black spot with a central point of white.
The essential points about "the flying gallop" are that the fore-limbs are fully stretched forward, the hind limbs fully stretched backward, and that the flat surfaces of the hinder hoofs are facing upwards.
The colour of the skin is a dusky lead, with some flesh-coloured marks on the belly, and the skin itself is an inch thick at its thickest part, on the back. Beneath the skin is a layer of fat, of great, thickness, which makes excellent oil when boiled. As we have said, the manati has no appearance of hind-limbs. Its fore-limbs, however, are highly developed for a water animal.
The ears are very minute holes, and the eyes are extremely small. The skin of the back is fully an inch thick; and beneath it is a layer of fat, also an inch or more in thickness. The fins of the fore-limbs consist of bones exactly corresponding to those of the human arm, with five fingers at the extremity every joint distinct, although completely encased in its thick inflexible skin.
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