54 



MUSEUM OF ANIMATED NATURE. 



[Squirrels. 



ORDER RODENTIA. 



The difficulty of instituting a natural arrangement 

 (ttiat is, an arrangement exhibiting the mullirorm 

 hnks and affinities uf different groups), is conress- 

 edly a work of difficulty ; but peculiarly so as it 

 respetis the component parts of the present order. 

 In itself, indeed, this order is definite, and based 

 upon characters which form a clear line of separation 

 between it and every other ; but when we come to 

 investigate the species it embraces, we soon feel 

 ourselves perplexed among a multitude of forms, 

 and begin to hesitate at every step. Hence it is 

 that no two naturalistu have arranged the Kodentia 

 in the same manner; nay, Cuvier himself, in the last 

 edition of his ' Rdgne Animal,' set aside the prin- 

 ciples by which in his earlier edition he was guided, 

 and followed out other views. 



Among those naturalists who have lately devoted 

 their attention to the Rodentia, Mr. Waterhouse 

 takes a foremost place ; and his arrangement, 

 founded on the truest philosophical principles, 

 is ti decided step in the advancement of this 

 department of Zoology. It would be out of 

 place, in a work like the present, to follow this 

 naturalist through his train of researches, but we 

 may give an outline of their results. Mr. Water- 

 house considers that the Rodents resolve themselves 

 into three great primary sections: first, the Murine 

 section; secondly, the Hystricine section; and 

 thirdly, the Leporine section. 



Each of these sections embraces several families, 

 each of the latter comprehending several genera. 

 The principal genera contained in the Murine sec- 

 tion are Sciurus, Arctorays, Spermophilus, Tamias, 

 Myoxus, Dipus, Mus, Arvicola, Geomys, and Castor. 

 The principal genera contained in the Hystricine 

 section are Bathurgus, Orycfenis, Poephagorays, 

 Octodon, Abrocoma, Myopotamus, Capromys, Echi- 

 mys, Aulacodus, Histrix, Dasyprocta, Chinchilla, 

 Cavia, and Hydrochaerus. The Leporine section 

 contains the genera Lcpus and Lagomys. 



Respecting a few genera, as Ctenodactylus, 

 Helamys, Otomys (Smitn, not F. Cuvier), Akodon, 

 and Heteromys, Mr. Waterhouse has not been able 

 to satisfy himself as to their precise systematic 

 classification ; and with respect to the genus Aplo- 

 dontia (Fig. 218, skull and teeth), though he places 

 it in the St^uirrel family (Sciuridae), yet it differs, as 

 he admits, in the absence of a post-orbital process 

 to the skull, and the molar teeth being rootless. 

 We may here remark that the genus Aplodontia 

 contains a Rodent, called by Lewis and Clark the 

 Sewellel(A. leporina),andwluch inhabits the neigh- 

 bourhood of the Columbia river (N. America), 

 where it lives in burrows, and associates in small 

 companies. The head is large, the nose is thick and 

 obtuse, covered with a dense coat of short fur; eye 

 very small ; ear resembling the human in form. 

 Body short, thick, and rabbil-like. Legs very short, 

 and covered down to the wrists and heels with fur 

 similar to that on the body : a little above the wrist 

 joint, on the inner side, is a small tuft of stiff white 

 hairs. Fur like that of a rabbit out of season, amber 

 and chestnut-brown above ; greyish or clove-brown 

 beneath ; lips whitish ; a rather large spot of pure 

 white on the throat ; some white hairs dispersed 

 through the fur. Tail slender, cylindrical, hardly 

 half an inch long. The figure (219) represents the 

 skull, teeth and paws: 1, anterior half of skull 

 with lower jaw, profile ; 2, anterior half of skull 

 seen from below ; 3, the same seen from above ; 

 4, lower jaw with right condyle broken, seen from 

 above ; 5, upper molar tooth ; 6, 7, fore-foot, upper 

 surface ; 8, sole of hind-foot. 



The Rodentia, as the name implies, have the 

 teeth constructed for gnawing, paring, or scramng 

 down the substances on which they feed. The 

 teeth are only of two kinds, incisors and molars. 

 There are no canines ; and between the incisors, 

 which project from the very apex of the jaws, and 

 the molars, which are situated far back, there inter- 

 venes an unfilled space of considerable extent. The 

 incisors are universally two in number in each jaw 

 (if we except the hares and rabbits, in which two 

 minute incisors rise at the back of the large perma- 

 nent ones) : these are strong, compressed, and some- 

 what curved, with sharp chisel-shaped edges. It is 

 only their anterior surface that is covered with a 

 thick layer of enamel, and this layer forms the cut- 

 ting edge, as does the layer of steel on softer metal 

 composing a common chisel. Their insertion into 

 their sockets is very deep, but the inserted part is 

 not a true root : these incisors spring from a pulpy 

 germ in their base, from which they are perpetually 

 growing, and this growth bears a due proportion to 

 the rapidity with which their cutting edges wear 

 away by use. So imperative is this law, that where 

 one incisor is lost by accident, its opposite, having 

 no countercheck, keeps increasing, till it acquires 

 an enormous development, to the annoyance, and 

 often the destruction, of the sufferer. With regard 

 to the molars it may be observed that they differ in 



number in different species: they are, however, 

 generally characterised by a flat surface ; traversed 

 transversely by ridges of enamel, their structure 

 being composed of perpendicular folds of this sub- 

 stance, compacted together by intervening osscus 

 matter; but further than this, wc find in different 

 species a structural distinction of physiological im- 

 portance : in some, as the Arvicoliclae, they resemble 

 the incisors, having no true solid roots, but are per- 

 petually growing as their surface wears away; in 

 others, on the contrary (as the squirrels), at a certain 

 period they gain truly formed roots, and alter this 

 cease all further growth. In the Rodentia the upper 

 lip, which is cleft longitudinally, is in many species 

 an organ of prehension ; or at least is of great im- 

 portance in gradually transmitting the food into the 

 mouth, as may be seen when we offer the rabbit a 

 leaf, or a stalk of clover, or dandelion. The pharynx, 

 or back of the mouth, is contracted, and in some 

 species funnel-shaped, and capable of being closed 

 by a circular muscle, in order that the food may pass 

 gradual ly , as it becomes duly ground to pulp between 

 the molars. The structural organisation of the 

 Rodents, as evidenced by the characteisof the skull, 

 the bird-like condition of the brain, and by other 

 points, is at a low par, and the ratio of their intelli- 

 gence is in a parallel degree. We may tame them, 

 but we cannot educate them. They are all timid 

 and feeble, and trust for self-protection to flight or 

 concealment The prey of ferocious beasts and 

 birds and reptiles, their fertility, by a wise provision, 

 counterbalances their annual diminution. Spread 

 over the earth, from the equator to the coldest lati- 

 tudes, they tenant rocks and mountains, plains and 

 woods, feeding on grain and vegetables, and often 

 devastating the cultivated domains of man. To a 

 vegetable diet some few, as the rat, add animal food 

 also. Most are nocturnal or crepuscular in their 

 habits ; many dwell in burrows, some conceal them- 

 selves amidst herbage, some amongst the foliage of 

 trees, and some build for themselves habitations 

 which have excited the interest and admiration of 

 man. 



In noticing the numerical abundance of the Ro- 

 dentia, throughout the different quarters of the 

 globe, it should be observed that in Australia six 

 or eight species are all that we are acquainted with 

 belonging to that region ; Europe, North America, 

 and South America are nearly equal as to the 

 number of species they contain. India and Africa 

 are also nearly equal, but they contain fewer species 

 than either of the other provinces. The squirrels, 

 rats, porcupines, and hares are the only groups 

 found in all the provinces ; all the rest of the 

 groups are respectively confined to their own par- 

 ticular geographical province. The naturalist will 

 find some important observations on the Rodentia 

 by Mr. Waterhouse, in the ' Zool. Proceeds.,' for 

 1839 ; in the ' Zool. of the Voyage of H.M.S. Beagle ;' 

 and in the ' Mag. of Nat. Hist.,' New Series, 1839, 

 p. 90. 



The squirrels (Fam. Sciuridae). These elegant 

 animals are distributed throughout every quarter of 

 the world, Australia excepted. The general cha- 

 racters of the true squirrels (Sciurus), as exhibited 

 by our well-known British species, are familiar to 

 all : its fine full eyes, its light contour, its activity, 

 its deep soft fur, and long bushy fail, have contri- 

 buted to render it a general favourite. They are 

 furnished with proper clavicles, or collar-bones, and 

 possess the use of the fore-arm and paws in a high 

 degree of perfection ; the toes are four, with the 

 rudiment of a thumb, on the anterior feet ; five on the 

 hind feet ; the claws are sharp and hooked. Mo- 



5 5 



lars, xZd- ^*™ often tufted with a pencil of long 



hairs. In feeding, these animals sit up on the 

 haunches, and hold their food (nuts, &c.) not 

 between the fingers of their joined fore-paws, but 

 between the rudimentary thumbs, while they work 

 at it with their teeth. 



220. — The Northern Grey and Black Sqciheel 



(Scitirtis leucotis). It is to Dr. Bachman, D.D., Pre- 

 sident of the Lit. and Phil. Soc, Charlestown, S. 

 Carolina, that we are indebted for clearing up the 

 mass of confusion in which the squirrels of America 

 have been involved. 



It appears from this author that several black 

 squirrels exist, totally distinct from each other, and 

 that of these some are mere varieties. Of the 

 genuine species he notices the large Louisiana black 

 squirrel (S. .\udubonii-), the black squirrel (Sciurus 

 niger, Linn., not Catesby), and the dusky squirrel 

 (S. nigrescens). There is a black variety of the 

 fox squirrel (Sc. capistratus), and a black variety 

 of the northern grey squirrel, the species figured. 

 The grey squirrels are numerous, and perplexing to 

 the naturalist. The Northern grey squirrel has been, 

 for instance, confounded with the Carolina grey 

 squirrel, from which it is distinct. The Northern 

 grey and black squirrel is a very common species, 

 and exceedingly active and sprightly. It is spread 



through the Northern and Middle States : it is abun- 

 dant in New York and in the mountainous parts of 

 Pennsylvania, and extends as far north as Hudi^on's 

 Bay : southwards, it occurs in Virginia, and perhaps 

 still farther south. 



Like all the true squirrels, this species is arboreal 

 in its habits, quick and alert :— it rises with the sun, 

 and continues industriously engaged in search of 

 food during four or five hours in the morning, ranning 

 over logs, ascending trees and playfully coursing 

 from limb to limb. During the warm weather of 

 spring it prepares its cradle or nest on the branch 

 of a tree, constructing it of dried sticks which it 

 breaks off, or, if these are not at hand, of green 

 twigs as thick as a finger, which it gnaws from the 

 boughs. These it lays in the fork of a tree or of 

 some large branch so as to make a framework : it 

 then lines this framework with leaves : and over 

 these again spreads a layer of moss. In the pre- 

 paration of this nest, a pair is usually engaged for 

 an hour in the morning, during several successive 

 days, and the noise they make in cutting the 

 branches and dragging the leaves may be heard at 

 some distance. In winter they reside entirely in 

 holes of trees, where their young in most instances 

 are brought forth. The young are from four to six 

 in number ; and in a few weeks are suflicieritly ad- 

 vanced to leave their nest. It is generally believed 

 that this squirrel lays up a great hoard of food as a 

 winter supply, but Dr. Bachman doubts the fact, 

 though he admits that other northern species do. 

 Further he states that the species which inhabit the 

 southern portion of the United States, where the 

 ground is seldom covered with snow, derive in 

 winter a precarious subsistence from seeds, insects, 

 and worms, which are scratched up among the 

 leaves. We may here observe that, singular enough, 

 no one has noticed the fact, excepting Mr. C. 

 Coward (' Mag. Nat. Hist.,' New Series, June, 1839, 

 p. 311), of our common British squirrel being car- 

 nivorous as well as frugivorous ; such is, however, 

 the case ; it attacks young birds and greedily devours 

 them, nor is evon the wood-pigeon safe from its 

 assaults. The Northern grey squirrel feeds on nuts 

 and v.arioiis seeds, but it seems to prefer the shell- 

 bark (Carya alba) and the several species of hickory 

 to any other food. Green com and young wheat 

 suffer greatly from its depredations, and hence a 

 war of wholesale destruction is everywhere waged 

 against it. In Pennsylvania an old law existed 

 offering threepence a head for every squirrel de- 

 stroyed, and in 1749 the enormous sum of 8000A 

 was paid out of the treasury for the destruction of 

 these depredators. The extensive migrations which 

 arc undertaken by this species, either from a scarcity 

 of food or from some other inexplicable cause, have 

 often excited not only wonder, but apprehension. 

 They generally take place in autumn, but by no 

 means with regularity. It would appear that in the 

 far north-west multitudes congregate in different dis- 

 tricts, forming scattered troops, which all bend their 

 way instinctively in an eastern direction, collecting 

 into larger bodies as they proceed; neither moun- 

 tains nor rivers stop their progress: onward they 

 come, a devouring army, laying waste the corn and 

 wheat fields of the farmer; and as their numbers 

 are thinned by the gun, others fill up the ranks: 

 few, perhaps none, ever return westwardly ; those 

 that escape the carnage take up their abode in the 

 forests of their newly-explored country. The grey 

 squirrel has many enemies; the fox, the lynx, the 

 weasel, hawks, and owls are all eager to seize it : 

 when attacked by the red-tailed hawk, its most for- 

 midable foe, it is amusing to see the skill and dex- 

 terity exercised by both, in the attack, and in the 

 defence ; often, indeed, the squirrel, by dodging and 

 twisting round the branches and large limbs of the 

 tree, foils and weare out his antagonist ; when, how- 

 ever, a pair of hawks combine, the squirrel has no 

 chance. 



221. — The Malabar Squirrel 



(Sciurus maximus). Of the Indian squirrels, one of 

 the finest is the Malabar squirrel, measuring four- 

 teen or fifteen inches in the length of the head and 

 body, and somewhat more in that of its full bushy 

 tail. This species is found in Malabar, and also in 

 Ceylon. Like the rest of its tribe, it is eminently 

 arboreal, tenanting the summits of palm-trees, anil 

 feeding to a great extent upon the cocoa-nut, to 

 the milk of which it is said to be very partial. We 

 have seen several specimens in captivity. They 

 soon become tame and familiar, but aie not to be 

 trusted too far : their bite is very severe. General 

 colour above, rich chocolate, deepening about the 

 shoulders into black ; under parts abruptly pale 

 reddish yellow ; ears tufted with a long full brush. 



222. — The Rocky-Mountain Flying Squirrkl 



(^Pteromys Alpinus, or Pt. Sabinus, var. ,8, Richard- 

 son). The flying squirrels (Petromys, Geofr. : Sci- 

 uropterus, F. Cuv.) agree in the general characters 

 of their dentition with the rest of the family (see Fig. 



