Fore feet with the functional toes reduced to two, the second and third, of equal length, with closely united metacarpals and short, sharp, slightly curved, compressed claws.
- The three fingers and their metacarpals remain separate, each with a claw.
- Metacarpals fused.
The Saururae have the metacarpals well developed and not ancylosed, and the caudal vertebrae are numerous and large, so that.
The second genus, Dorcatherium (or Hyomoschus), is African, and distinguished chiefly by the feet being stouter and shorter, the outer toes better developed, and the two middle metacarpals not welded together.
The middle metacarpals and metatarsals generally confluent, the outer ones (second and fifth) slender but complete, i.e.
The most interesting genera are, however, the Upper Oligocene and Lower Miocene Gelocus and Prodremotherium, which have perfectly selenodont teeth, and the third and fourth metacarpal and metatarsal bones respectively fused into an imperfect cannon-bone, with the reduction of the lateral metacarpals and metatarsals to mere remnants of their upper and lower extremities.
In the forelimbs the bones corresponding to the third and fourth metacarpals of the pig's foot are fused into a cannon-bone; and a similar condition obtains in the case of the corresponding metatarsals in the hind-limbs.
(X i .) Lateral digits of both fore and hind feet almost always present, and frequently the lower ends of the metacarpals and the metatarsals as well.
Lower ends of the lateral metacarpals and metatarsals never present.
Here the metacarpals and metatarsals have partially united to form cannonbones, the skull has assumed the elongated form characteristic of modern camels, with the loss of the first and second pairs of upper incisors, and the development of gaps in front of and behind each of the next three teeth, that is to say, the third incisor, the canine and the first cheek-tooth.
In one species of Procamelus the metacarpals and metatarsals coalesced into canon-bones late in life; but when we come to the Pleistocene Camelops such union took place at an early stage of existence, and was thoroughly complete.
The tail is very long; and the feet have five functional toes, with complete but short metacarpals or metatarsals.
The hand skeleton consists of 3 completely separate metacarpals, each carrying a corn FIG.
The whole wing is consequently, although essentially avine, still reptilian in the unfused state of the metacarpals and the numbers of the phalanges.
- Lateral metacarpals as in preceding; antlers (as in the following genera) present only in the male, arising at right angles to the median longitudinal line of the skull, and extending at first in the plane of the forehead, after which, when in their fullest development, they expand into a broad palmation margined with snags.
- Lateral metacarpals represented only by their upper ends.
- Lateral metacarpals as in Cervus; antlers small, with a brow-tine and an unbranched beam, supported on long bony pedicles, continued downwards as convergent ridges on the forehead; upper canines of male large and tusk-like.
- Lateral metacarpals as in Rangifer; antlers wanting; upper canines of males tusk-like and growing from semi-persistent pulps; cheek-teeth tall-crowned (hypsodont); tail moderate.
- Lateral metacarpals as in Rangifer; antlers rather small, without a brow-tine or sub-basal snag, dichotomously forked, with the upper or posterior prong again forking; tail rudimentary; vomer not dividing posterior nasal aperture of skull.
- Lateral metacarpals as in Cervus; antlers large, without a brow-tine or sub-basal snag, dichotomously forked, with the upper prong of the fork curving forwards and dividing, and the lower prong long, simple, and projected backwards, the beam making a very marked angle with the plane of the face; tail very long; vomer as in Capreolus.
- Lateral metacarpals as in Rangifer; antlers very variable in size, forming a marked angle with the plane of the face, without a brow-tine; when consisting of more than a simple prong, dichotomously forked, frequently with a subbasal snag, and always with the lower prong of the fork projected from the front edge of the beam, in @ome cases the lower, in others the upper, and in others both prongs again dividing; tail long; tarsal gland generally present; metatarsal gland very variable, both as regards presence and position; vomer dividing the inner aperture of the nostrils in the skull into two distinct chambers.
- Skull and metacarpals generally as in Mazama; size very small; hair coarse and brittle; antlers in the form of short, simple spikes; cannon-bones very short; tail very short or wanting; no whorls in the hair of the face; face-gland moderately large, and gland-pit deep and oval; tarsal and metatarsal glands wanting; ectocuneiform bone of tarsus united with the naviculocuboid.
- Hair coarse and brittle; upper canines of male very long; no tarsal or metatarsal glands or tufts; lateral metacarpals represented by their lower extremities; lateral hoofs very large; tail very short; naked portion of muzzle extensive; male with a large abdominal gland.
The large metacarpal is called in veterinary anatomy " cannon bone"; the small lateral metacarpals, which gradually taper towards their lower extremities, and lie in close contact with the large one, are called " splint bones."