This section is from the book "General Outline Of The Organization Of The Animal Kingdom, And Manual Of Comparative Anatomy", by Thomas Rymer Jones. Also available from Amazon: A General Outline of the Animal Kingdom and Manual of Comparative Anatomy.
(2217). Among all the countless races of the animal kingdom, Man alone is permitted, in a state of nature, to arrive at old age; that is to say, at such an age as to allow feebleness and decrepitude to usurp the place of strength and activity. Man only is capable of such a privilege, because he alone possesses that foresight which enables him to prepare in youth against the decline of his faculties, and is endowed with sympathies and affections directing the strong and the vigorous to maintain the aged and the infirm.
(2218). Among the lower animals, sickness and decay are not permitted to exist. Activity and health alone are conspicuous throughout the broad creation: disease and decline are banished from the world. Does any creature lack but for a brief period its accustomed powers of escape, the destroyer is at hand instantly to remove it from its appointed sphere of action. Butchers are placed on all sides, ready to perform their office; and nothing is permitted to live but what possesses its faculties and its strength unimpaired and unenfeebled.
Fig. 391. Skeleton of the Jerboa.
(2219). The great character that distinguishes the Carnivorous quadrupeds is the high degree of intelligence and activity for which they are so remarkable. The perfection of their limbs and the acuteness of their senses at once indicate their superiority over the Herbivorous races; and their jaws, armed with powerful fangs, usually distinguished by the name of canine teeth, show at a glance the nature of their appointed food and their murderous propensities.
(2220). The distribution of these tyrants of the animal creation we shall find to be coextensive with that of the victims they are appointed to destroy.
(2221). The aquatic tribes of the Carnivora (Amphibia, Cuv.) are obviously constructed for swimming. Their bodies, covered over with short, close, and polished hair, taper off towards each extremity, resembling in form those of the Cetaceans. The cervical, thoracic, and lumbar regions of the spine are light and flexible; and the pelvis is contracted, and placed as far back as possible. Both the anterior and posterior extremities, although completely formed, are short, and in the living animal are only free externally as far as the carpal and tarsal joints. The feet, moreover, are broadly webbed, and thus become converted into most efficient paddles, by the aid of which these creatures swim with astonishing ease and elegance, the hinder pair performing at once the functions of oars and rudder. Upon land, however, their movements are, as might be supposed, extremely clumsy: it is true that they not unfrequently scramble on to the beach, there to bask in the sun, or to suckle their little ones; but if danger threatens, they immediately take to the water, and fall easy victims if their retreat towards the sea be intercepted.
Fig. 392. Skeleton of the Seal.
(2222). Such being the helplessness of the Seals when they quit the water for the shore, it is not surprising that, in some of the larger and more unwieldy forms, assistant locomotive organs have been given, derived from unlooked-for sources. Thus in the Walrus (Trichechus rosmarus), which apparently obtains nourishment from the fad of the shore, as well as by destroying living prey, even the canine teeth of the upper jaw are converted into instruments of progression, and serve as crutches to drag the animal along. In these creatures the upper jaw is extremely dilated and massive, and the canine teeth implanted in it not unfrequently project downwards to a distance of from one to two feet from the mouth. The strength of the tusks so formed is proportionate to the bulk of this gigantic Seal, and by their aid the Walrus is enabled to climb on to the rock in order to repose after its labours in the ocean.
(2223). The Terrestrial Carnivora, that live upon flesh, are naturally divisible into two great sections. Of these, the most cruel and bloodthirsty, that walk only upon their toes, and are called from this circumstance "Digitigrada," bound along with an elasticity and swiftness that are abundantly provided for in the construction of every part of their osseous system. In this section are classed the extensive tribes of Weasels (fig. 393), Civets, Hyenas, and the race of Cats, the most formidable and ravenous of quadrupeds.
Fig. 393. Skeleton of the Weasel.
(2224). In the Feline Carnivora, indeed, to which belong the Lion and the Tiger, so justly celebrated for their strength and ferocity, a peculiar and beautiful provision is visible in the construction of the foot, whereby the claws that arm the last phalanges of the toes are kept constantly sharp, their points never being allowed to become worn by touching the ground; hence they are in these creatures terrific instruments of attack. The mechanism provided for effecting this is as follows: - three elastic ligaments, derived from the penultimate joint of the toe, are inserted into the last phalanx in such a manner that, by their elasticity, under ordinary circumstances, they keep the claw laid back upon the upper aspect of the foot; so that, the soft cushions beneath the toes being the only parts brought in contact with the ground, these creatures always walk with a stealthy and noiseless tread. But when the Tiger springs upon his prey, the tendons of the flexor muscle of the toes, implanted into the opposite surface of the phalanx, overcoming the elasticity of the retractile ligaments, pluck forward the curved claws, and burying them deeply in the flesh of the victim, the strongest animals struggle vainly to shake off a gripe so tenacious.
(2225). But, among the Digitigrade Carnlvora, none are of so much importance as the Dog - an animal specially provided for the use of man, to be his companion in the field, and his assistant at the chase.