The species are all characterized by short rudimentary wings, bearing four or five barbless shafts, a few inches long, and apparently useless for purposes of flight, of running, or of defence; and by loosely webbed feathers, short on the neck, but of great length on the rump and back, whence they descend over the body forming a thick hair-like covering.
It was surprising to see how serenely he sailed off with unruffled breast when he came to the surface, doing all the work with his webbed feet beneath.
The tail is about half the length of the head and body, and the hind feet are long and powerful, although not webbed, and have five rounded pads on their lower surfaces.
Order Colymbiformes.-Plantigrade, nidifugous, aquatic. All toes webbed, fourth largest, hallux short; metatarsus laterally compressed; tibia with high, pyramidal crest.
The genus Rana may be defined as firmisternal Ecaudata with cylindrical transverse processes to the sacral vertebra, teeth in the upper jaw and on the vomer, a protrusible tongue which is free and forked behind, a horizontal pupil and more or less webbed toes.
In some polyps the tentacles are webbed at the base, and it was supposed that a medusa was a polyp of this kind set free, the umbrella being a greatly developed web or membrane extending between the tentacles.
It differs from the true crocodile principally in having the head broader and shorter, and the snout more obtuse; in having the fourth, enlarged tooth of the under jaw received, not into an external notch, but into a pit formed for it within the upper one; in wanting a jagged fringe which appears on the hind legs and feet of the crocodile; and in having the toes of the hind feet webbed not more than half way to the tips.
Some of the species are thoroughly aquatic and have fully webbed toes, others are terrestrial, except during the breeding season, others are adapted for burrowing, by means of the much-enlarged and sharp-edged tubercle at the base of the inner toe, whilst not a few have the tips of the digits dilated into disks by which they are able to climb on trees.
Front toes completely webbed; hallux very short or absent; feed chiefly on small aquatic invertebrates.
The number of eggs produced at a time varies enormously according to the species, from about half a dozen, more or less, in some ant-mimicking Attidae or jumping spiders to many hundreds in the larger orbicular-webbed spiders of the family Argyopidae.
Their feet are all more or less webbed, but in swimming they are said to keep these organs motionless by their sides.
Westlake plugged forward, his nose nearly at the windshield, which was spider-webbed with nicks and cracks, as the old car crawled higher.
In the beavers or Castoridae these bones are in close contact at their lower ends, the tail is depressed, expanded and scaly, and the habits are aquatic. Beavers have webbed hind-feet, and the claw of the second hind-toe double.
The king bird of paradise (Cicinnurus regius) is one of the smallest and most brilliant of the group, and is specially distinguished by its two middle tail feathers, the ends of which alone are webbed, and coiled into a beautiful spiral disk of a lovely emerald green.
In size they may be compared with cats; the long slender limbs are connected by a broad fold of skin extending outwards from the sides of the neck and body, the fingers and toes are webbed, and the hind-limbs joined by an outer membrane as in bats.
CAPYBARA, or Carpincho (Hydrochaerus capybara), the largest living rodent mammal, characterized by its moderately long limbs, partially-webbed toes, of which there are four in front and three behind, hoof-like nails, sparse hair, short ears, cleft upper lip and the absence of a tail.
Hydrochaerus, in which all the feet are fully webbed, includes a single species, the capybara, or carpincho, the largest of living rodents.
Its large size, aquatic habits, partially webbed hind-toes, and the smooth, broad, orange-coloured incisors, are sufficient to distinguish this rodent from the other members of the family Capromyidae.