It was beautifully soft, glossy, and brown. The skins were about the size of a large rat’s, and about twenty in number. Here, then, was the dawn of a discovery. He called the animal Ou-ka-la, and made me understand that it lived on roots and vegetable matter, and burrowed holes in the ground.
As the daylight faded out, I again took my seat; and, just as before, when everything was silent, the woods echoed with the Ou-ka-la’s cry. I longed for morning, and hardly waited for light, but hastened off to my trap and, joy of joys, I had one sure enough, caught by the neck. Poor Ou-ka-la! your friends had heard, and you had given, your ‘last whistle.’ He was dead and cold—trapped, perhaps, whilst I listened wonderingly, keeping my lonely vigil. A very brief examination revealed the fact that I had caught a magnificent specimen of the Aplodontia leporina, of which I had only read.
Captains Lewis and Clark obtained some vague information about this animal, which is given in their journal of travel across the Rocky Mountains, in 1804. All they say of its habits is, ‘that it climbs trees, and digs like a squirrel.’ They obtained no specimen of the animal, but saw, probably, robes made of the skins. It was subsequently described by Rafinesque, and by him named Anysonyx rufa, and by Harlan Arctomys rufa. In 1829 Sir John Richardson obtained a specimen, and, after a careful anatomical examination, this eminent naturalist determined it to be a new genus, and renamed it, generically and specifically. The generic name (Aplodontia) is founded on its having rootless molars, or grinding teeth—aploos, simple; odons, a tooth. It belongs to the sub-family Castorinæ, dental formula 2 00 55/2 00 44 22.
Sp. ch.—Size, that of a musk-rat; tail very short, barely visible; colour, glossy blackish-brown. Male, length about 14 inches; female resembling the male, but smaller. The fur is dense and woolly, with long bristly hairs, thickly interspersed; the short fur is bluish-gray at the base, the ends of the hairs being tipped with reddish-brown; the bristles are black, and when smooth give a lustrous appearance to the fur. The eyes are very small, and placed about midway between the nose and the ear. The whiskers, stiff and bristly, are much longer than the head, and dark grey. The ears are covered on both sides with fine soft hair, rounded and very short, and not unlike the human ear.
Skull.—The skull is much like that of the squirrel’s, with the marked exception of having rootless molars, and the absence of post-orbital processes; the occipital crest is well-developed, the muzzle large, and nearly round. The bony orbits are largely developed; the auditory bullæ are small, but open at once into wide auditive tubes; the first molar is unusually small, oval, and situated against the antero-internal angle of the second. All the molars are rootless: the lower grinders are much like the upper, but somewhat longer and narrower. The molars in both jaws are situated much farther back than is usual, the centre of the skull being about opposite to the meeting of the second and third. The lower jaw is very singularly shaped, the inner edges of the molars on opposite sides being parallel; the descending ramus is bent, so as to be exactly horizontal behind, the postero-inferior edge being a straight line, nearly perpendicular to the vertical plane of the skull’s axis. The conformation of the incisor-teeth is admirably adapted to the purposes they have to fulfil; no carpenter’s gouging chisels are more effective tools than are these exquisitely-constructed teeth. It is essential that they should always have a sharp-cutting edge, in order to nip through the tough vegetable fibre on which the animal subsists; at the same time, strength and durability are indispensable. The Aplodontia has no whetstone or razor-grinder, to sharpen his tools when they grow blunt; but an Allwise Providence has so fashioned these wondrous chisels in all rodents, that the more they are used the sharper they keep; the contrivance is simple as it is beautiful. The substance of the tooth itself is composed of tough ivory, but plated on the outer surface with enamel as hard as steel. The ivory, being the softer material, of course wears away faster than the enamel; hence the latter, plating the front of the tooth, is always left with a sharp-cutting edge.
The position this genus should occupy, in a systematic arrangement of the rodents, has always been a stumbling-block and a matter of doubt, in great measure attributable to the fact that but a single species of the genus is known, and very few specimens have hitherto been obtained. A fine male specimen has recently been set up in the British Museum collection, that I caught near my camp on the prairie.
In many particulars the Aplodontia very nearly resembles the Spermophiles, particularly the prairie-dog (Cynomys Ludovicciana), but differs, as in the true squirrels, in the rootless molars and absence of post-orbital processes. In this respect it is allied to the beaver. It is quite impossible to assign it a well-defined and settled position, until a greater number of specimens are procured, from which more minute and careful examination of the bony and internal anatomy can be made. At present, however, it would appear to connect the beavers with the squirrels, through the Spermophiles.
The name Lewis and Clark gave this animal, Sewellel, is evidently a corruption of an Indian word. The Chinook Indians, once a powerful tribe, live near the mouth of the Columbia; and from them, in all probability, Lewis and Clark obtained the name, and first heard of the animal. But the Chinook name for the Aplodontia is Ogool-lal, Shu-wal-lal being the name of the robe made from the skins; and this is unquestionably the word corrupted into Sewellel, and misused as the name of the animal. In Puget’s Sound the Nesqually Indians call it Show′tl; the Yakama Indians, Squal-lah; and the Sumass Indians, Swok-la.
A single glance at the conformation of the feet would at once convince the most careless observer that climbing trees was not a habit of the Aplodontia. The feet and claws are digging implements, of the most finished and efficient kind: the long scoop-shaped nails, resembling garden trowels; wide strong foot, almost hand-like in its form; the strong muscular arms, supported by powerful clavicles, proclaim him a miner; his mission is to burrow, and most ably he fulfils his destiny. His haunt is usually by the side of a stream, where the banks are sandy, and the underbrush grows thickly; his favourite food being fine fibrous roots, and the rind of such as are too hard for his teeth. He spends his time in burrowing, not so much for shelter and concealment, as to supply himself with roots. He digs with great ease and rapidity, making a hole large enough for a man’s arm to be inserted.
In making the tunnels, he seldom burrows very far without coming to the surface, and beginning a new one. Like a skilful workman, he knows how to economise labour. Having to back the earth out of the mouth of the hole he is digging, the farther he gets in the harder grows the toil; and so he digs up through, and starts afresh. They seldom come out in the daytime, and I have but rarely heard them whistle until everything was still, and the twilight merged into night.