66 



THE EDINBURGH JOURNAL OF NATURAL HISTORY, 



Account of a PaETERNATuaAi. Growth of the Incisort Teeth of a Rab- 

 bit In the class Rodentia of Cuvier, of which the Rabbit is a member, there not 



unfrequently occurs an extraordinary development of the incisory or cutting teeth. 

 It is a well established point in physiology, that those teeth, like the tusks of the 

 Elephant, are in a constant state of growth, and that they emanate from long roots 

 nearly equal in length to the jaw; they curve backwards under the molar teeth, 

 extending in some instances as far back as the coronoid process. Owing to this beauti- 

 ful adaptation of Nature to the habits of the tribe, there is a constant, gradual ad- 

 vancement of tho interior part of the teeth, to supply that portion worn down by 

 friction, while the animal is feeding or gnawing substances — for which tha Rodentia 

 have a strong propensity. Under ordinary circumstances, this gradual increase is so 

 admirably regulated, that the cutting edges of tho two pair of incisory teeth uniformly 

 preserve the same relative situation. 



The above figure represents the head of a wild Rabbit, which is preserved in the 

 private museum of Mr Robert Frazer, jeweller, 17, St Andrew's Street, Edinburgh; 

 with an extraoi-dinary elongation above the gums, of both the upper and under inci- 

 sors, the former measuring an inch and five-eighths, and reaching considerably above 

 the nostrils, while the latter is seven-eighths of an inch in length, and very much in- 

 curved, so much so, that their points would nearly reach the palate when the mouth 

 IS closed. The under incisors are also considerably bent, becoming gradually thinner 

 and more depressed towards their points, where they are divergent, the inner sides 

 being nearly a quarter of an inch apart at the tips. Their ordinary length in the wild 

 Rabbit is about a quarter of an inch. Instances of the same kind have been noticed 

 before, in Plott's History of Staffordshire ; in Morton's Natural History of North- 

 amptonshire ; and in Loudon's JMagazine, where an account of a lusus of this kind is 

 given by the Rev. L. Jenyns, the object of which is preserved in the Museum of the 

 Cambridge Philosophical Society. 



Cuvier says, that the prismatic form of the cutting teeth occasions them to grow 

 from the root as fast as they wear away at the edge ; and this tendency to increase 

 in length is so powerful, that if one of them be lost or broken, the opposite one in 

 the other jaw having nothing to oppose or communicate, becomes developed to a mon_ 

 sfrous extent. The elongation of the teeth in the specimen now before us, could 

 not have been occasioned by any accident of this kind, as the development is exces- 

 sive in both upper and under teeth, while none of them evince the slightest appear- 

 ance of having been fractured. Therefore some other mode of accounting for this 

 instance must be sought for, and we would rather attribute it to the unequal action 

 of the jaws, in the under one not being exactly opposed to the upper. 



Mr Jenjms supposes that this preternatural elongation may arise either from the 

 food being too soft, or too rapid a secretion of the osseous matter which composes 

 the teeth, or a derangement of the under jaw, produced from a dislocation or some 

 other cause ; and to one or other of these he attributes two of the cases which fell under 

 his own observation. In the case of the rabbit's head preserved in the Cambridge 

 Philosophical Society, which, so far as the length and disposition of the lower in- 

 cisors are concerned, agrees very nearly with our case, he considers that it was oc- 

 casioned by too rapid a secretion of the osseous matter ; and in the second case, 

 both upper and under incisors were preternaturally elongated ; " but then,' says he, 

 "in this instance there was such an irregularity in their mode of growth, that we 

 may perhaps find a better explanation of the anomaly in some derangement of the 

 jaws, the result either of natural constitution or of accidental injury. 'Whatever 

 this might have been (for I regret that this rabbit was not preserved, and an exami- 

 nation made of the jaws at the time), the effect was that of causing the lower pair 

 of incisors, when viewed together, to assume the shape and appearance of the letter 

 V, diverging from one another at the surface of the gum, and extending in opposite 

 directions, to the length of nearly an inch and a half. The degree of divergency 

 observed in the upper pair was nearly as great as this in the lower, and their 

 length about the same ; but their curvature very much greater ; as indeed would 

 naturally result from the greater bend of that portion of the jaw in which these in- 

 cisors are formed. In this instance, the portion without the gums had completed 

 three parts of an exact circle, and their cutting edges were in close contact with the 

 roof of the mouth." 



Both of the rabbits above referred to, when captured, were nearly starved to death 

 from their incapacity to eat their usual food. In that first noticed, the animal seemed 

 to exist solely by means of the small quantity of food which it could nip by the hps 



at the sides of the mouth, which exhibited maris of its having been used for that 

 purpose. Our specimen has no such appearance. In the second case mentioned by 

 Jenyns, the poor animal was unable to close its mouth, from the curve of the upper 

 incisors pressing upon the tongue. These two were found in the neighbourhood of 

 Cambridge. 



Mr Jenyns mentions a third individual, from Lincolnshire, one of whose incisorv 

 teeth was still longer than any of the others mentioned, which had grown into the 

 palate, and re-entered that portion of the jaw from whence it sprung, which appeared 

 to have been produced by some local disease, affecting, in the first place, that single 

 tooth, which was much twisted in its direction. 



The specimen which has come under our notice was found dead from starvation 

 in the rabbit-warren at Lcven Links, Fifeshire, Scotland ; and exhibited signs of 

 great emaciation, from its inability to feed. 



The Chow and Rat — In the spring of the year 1834, while a person was cross- 

 ing a field, in an elevated and retired situation, in the parish of Kirk-Marown, Isle 

 of Man, he perceived a Crow flying at a short distance from him which attracted his 

 attention. On account of the unusual noise which it made, and while watching its 

 strange motions, he was able to perceive that it had some object suspended from its bill, 

 which dropped in a few seconds, while the bird was almost flying over him. He 

 immediately hastened towards it, and found it to be a young Rat more than half- 

 grown. It was still alive, but somewhat stunned by the fall. This happened at the 

 time that the young Crows were in the nest, and doubtless was intended for food to 

 them. The particular noise made by the Crow must have been occasioned by the 

 efforts of the Rat to disengage himself from his a'erial foe. — (Communicated by a 

 " Young Naturalist," Bu-mingham, August 1836). 



BOTANY. 



On the Shamrock of Ireland. — Mr Bicheno has laid before the Linnean Society 

 a paper " on the plant intended bythe Shamrock of Ireland;" in which he attempted 

 to prove, by botanical, historical, and etymological evidence, that the original plant 

 was not tho white clover which is now employed as the national emblem. He stated, 

 that it would seem a condition at least suitable, if not necessary, to a national emblem, 

 that it should be something familiar to the people — and familiar, too, at that season whec 

 the national feast is celebrated. Thus, the Welsh have given the leek to St David, 

 being a favorite olearaceous herb, and the only green thing they could find on the first 

 of March; — the Scotch, on the other hand, whose feast is in November, have 

 adopted the thistle. The white clover is not fully expanded on St Patrick's day, 

 and wild specimens of it could hardly be obtained at this season. Besides, it was 

 probably, nay, almost certainly, a plant of uncommon occurrence in Ireland during 

 its early history, having been introduced into that country in the middle of the 

 seventeenth century, and made common by cultivation. Several old authors affirm, 

 that the shamrock was eaten by the Irish ; one of which, who went over to Ire- 

 land in the sixteenth century, says it was eaten, and that it was a sottr plant. The 

 name Shamrock is common also to several trefoils, both in the Irish and Gaelic 

 languages. Now, the clover could not have been eaten, and it is not sour. Taking, 

 therefore, all tho conditions requisite, they are only found in the Wood-sorrel, oxjlis 

 acetosella. It is an early spring plant; it was, and is, abundant in Ireland; it is a 

 trefoil ; it is called Sham-rog by the old herbalists, and it is sour ; while its beauty 

 might entitle it to the distinction of being the national emblem. The substitution 

 of one for the other has been occasioned by cultivation, which made the Wood-sorrel 

 less plentiful, and the Dutch clover abundant. 



MINERALOGY. 



The Diasiond — This precious Stone, in its natural state, is of the form of an 

 octahedron. This may be defined a double four-sided pyramid, in which the lateral 

 planes of the one ai-e set on the lateral planes of the other, which will be better 

 understood by the accompanying figure, being a regular 

 octahedron, wherein the triangular faces are equilateral 

 and equiangular, and, of course, the base of the two pvra- 

 mids is a square. Diamonds are always found in detached 

 crystals, and are more or less well shaped, as they are 

 pure or otherwise ; so that they occur in a variety of 

 forms, of which their primitive one is the basis ; the faces 

 are frequently curvilinear ; they are also subject to the 

 compound crystallization called the made. The structure is perfectly lamellar, 

 yielding readily to mechanical division parallel to all the planes of the regular oc- 

 tahedron, thus proving tliat this is the primitive form. Diamond is the hardest of 

 all substances, and its specific gravity 3.5. W'hen heated, it becomes phospho- 

 rescent. The general colour of the Diamond is w*hite, but is found of various tints, 

 red like the Ruby, orange like the Hyacinth, blue like the Sapphire, and green 

 hke the Emerald ; the last of which is most rare, and of the greatest value when it is 

 of a beautiful tint ; the rose, blue, and yellow Diamonds are the next in value. 

 Transparency and brilliancy are the natural and ordinary qualities of the Diamond 

 which exhibits but a single refraction of the rays of hght ; some, however, are quite 

 opaque. Diamonds are divided into Oriental and Occidental or BraziUan, the former 

 being the most valuable. Eostius de Boot, in his *' History of Gems," written in 

 1609, conjectured that the Diamond was inflammable. Mr Boyle discovered, in 1673, 

 that when exposed to a high temperature, it gave out acrid vapours, in which a pan 

 of it w*as dissipated. Sir Isaac Newton, who composed his work on Optics in 1675, 

 concluded, from its gi'eat refracting power, that it must be combustible, and that it 

 might be an unctuous substance coagulated. But the celebrated Averani, in 1695, 

 in presence of the Grand Duke of Tuscany, and several of the most philosophic men 

 of that time, showed, by concentrating the rays of the sun upon it, that the Diamond 

 was exhaled in vapour and disappeared entirely, while other precious Stones only 



