No\-EMBER 1. 1893.] 



X Jiv^ 



KNOWLEDGE 



201 



,>^- ixv\^^ 



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^^ AN ILLUSTRATED "^^ 



MAGAZINE OF SCIENCE 



SIMPLY WORDED— EXACTLY DESCRIBED 



LONDON: NOVEMBER 1, 1893. 



CONTENTS. 



PAGE 



The Tallest Mammal. By R. Ltdekkee, B.A.Cantab. ... 201 

 The Making of Mountain Chains. By H. G. Welis, B.Sc. 204 

 Letters:^ Agnes M. Olerrk ; .T. Evershed; Aethue 



SmITHELLS ; W. E. WiLsox ; R. S. JIUTCHIJfGS ; W. H. 8. 



MONCK ..i ... 206 



The Tints of the Lunar Plains. By A. C. Raxyakd... 209 



Science Notes 212 



Lexell's Comet and the question of its possible 



identity with Comet V, 1889. By W. T. Lynn, 



B.A., F.R.A.S 213 



Dust and Atmospheric Phenomena. By Dr. J. G. 



McPherson, F.R.S.E 21-i 



Curious Cocoons— I. By E. A. Butler 214 



The Face of the Sky for November. By Heebeet 



Sadlee, F.R.A.S 218 



Chess Column. By C. D. Locoes, B.A.Oxon 219 



THE TALLEST MAMMAL. 



By E. Lydekker, B.A.Cantab. 



COMPARED with their extinct allies of earlier periods 

 of the earth'.s history, it may be laid down as a 

 general rule that the large animals of the present 

 day are decidedly inferior in point of size. During 

 the later portion of the Tertiary period, for instance, 

 before the incoming of the glacial epoch, when mammals 

 appear to have attained their maximum development, there 

 lived elephants alongside of which ordinary indi\-iduals of 

 the existing species would have looked almost dwarfs, while 

 the cave bear and the cave hyaena attained considerably 

 larger dimensions than their living representatives, and 

 some of the sabre-toothed tigers must have been con- 

 siderably larger than the biggest African lion or Bengal 

 lion. Again, the remains of red deer, bison, and wild 

 oxen, disinterred from the cavern and other superficial 

 deposits of this country, indicate animals far superior in 

 size to their degenerate -descendants of the present day ; 

 while some of the extinct pigs from the Siwalik Hills of 

 northern India might be compared in stature to a tapir 

 rather than to an ordinary wild boar. The same story is 

 told by reptiles, the giant tortoise of the Siwalik Hills, in 

 spite of its dimensions having been considerably exaggerated, 

 greatly exceeding in size the largest living giant tortoises 

 of either the Mascarene or the Galapagos Islands. The 

 latter rocks have also yielded the remains of a long- 

 snouted crocodile, allied to the garial of the Ganges, 

 which probably measured from fifty to sixty feet in length, 

 whereas it is very doubtful if any existing member of the 



order exceeds half the smaller of these dimensions. If, 

 moreover, we took into account totally extinct types, such 

 as the niegatheres and mylodons of South America, and 

 contrasted them with their nearest living allies — in this 

 instance the sloths and anteaters — the discrepancy in size 

 would be still more marked, but such a comparison would 

 scarcely be analogous to the above. 



To every rule there is, however, an exception, and there 

 are a few groups of living large mammals whose existing 

 members appear never to have been surpassed in size by 

 their fossil relatives. Foremost among these are the 

 whales, which, as we have seen in a previous article, now 

 appear to include the largest membei'S of the order which 

 have ever existed. The so-called white, or square-mouthed, 

 rhinoceros of South Africa seems also to be fully equal in 

 size to any of its extinct ancestors ; and the same is 

 certainly true of the giraffe, which may even exceed all its 

 predecessors in this respect. Whether, however, the fossil 

 giraffes, of which more anon, were or were not the equals 

 in height of the largest individuals of the living species, 

 there is no question but that the latter is by far the tallest 

 of all living mammals, and that it was only rivalled in this 

 respect among extinct forms by its aforesaid ancestors. 

 Moreover, if we exclude creatures like some of the gigantic 

 dinosaurian reptiles of the Secondary epoch, which, so to 

 speak, gained an unfair advantage as regards height by 

 sitting up on their hind legs in a kangaroo -like manner, 

 and limit our comparison to such as walk on all four feet 

 in the good old-fashioned way, we shall find that giraffes 

 are not only the tallest mammals, but likewise the tallest 

 of all animals that have ever existed. 



In the great majority of animals that have managed to 

 exceed all their kin in height, the increment in stature has 

 been arrived at by lengthening the hind limbs alone, and 

 thus making them the sole or chief support of the body. 

 In some of these cases, as among the li\'ing kangaroos 

 and the extinct dinosaurs, the body was raised into a more 

 or less nearly vertical position, and the required height 

 attained without any marked elongation of the neck. In 

 birds, on the other hand, like the ostrich, the body is 

 carried in nearly the same horizontal position as in a 

 quadruped, but both the hind legs and the neck have been 

 elongated. The girafl'e, however, has attained its towering 

 stature without any such important departure from the 

 general structure characterizing its nearest allies, and thus 

 preserves all the essential features of an ordinary quad- 

 ruped. Belonging, as we have had occasion to mention 

 in an earlier article, to the great group of ruminant 

 ungulates, among which it is the sole living representative 

 of a separate family, the girafl'e owes its height mainly to 

 the enormous elongation of two of the bones of the legs, 

 coupled with a corresponding lengthening of the vertebrae 

 of the neck. As in all its kindred, the lower segment of 

 each leg of this animal forms a cannon-bone, the nature 

 of which has been explained in the article referred to ; 

 and in the fore limb it is the bone below the virrist (com- 

 monly termed the knee), and the radius above the latter, 

 which have undergone an elongation so extraordinary as 

 to make them quite unlike, as regards proportion, the 

 corresponding elements in the skeleton of a ruminant, 

 such as an ox, although retaining precisely the same 

 structure. Similarly, in the hinder limb, it is the cannon- 

 bone below the ankle joint or hock, and the tibia or shin- 

 bone above, which have been thus elongated. To anyone 

 unacquainted with their anatomy, it might well appear 

 that a giraffe and a hippopotamus would difl'er greatly 

 in regard to the number of vertebra in their necks ; but, 

 nevertheless, both conform in this respect to the ordinary 

 mammalian type, possessing only seven of such segments. 



