August, 1903.] 



KNOWLEDGE. 



1G9 



Founded by RICHARD A. PROCTOR. 

 Vol. XXVI.] LONDON : AUGUST, 1903. [No. 214. 



CONTENTS. 



^ PAGE 



The Ancestry of the Elephant. Bv R. Ltdf.kker. 



{Uliistrated) " 169 



Murray and Chrystal on "Seiches." By Dr. J. Gr. 



MrPiiEKSOX, F Rs K (Illii.slrateil) 172 



Wireless Telegraphy and Weather Forecasting. By 



Akthue U. Bell 172 



The Dark Hemisphere of Venus. By B. W. Lane ... 175 

 The Chemistry of the Stars. IV. — Stars of the First 



Type. By A. Fowleh, f.r..\.s. {llhistrafed) 176 



Jupiter and his Markings. By W. F. Denning, f.e.a.s. 



(Illustrated) {Plate) ..'. 177 



Letters : 



" MOLECUIE'! AND HeAT." By FREDERICK HoVENDEN... 180 



Rare Condition OFTifE Human Hair. By W. S. Rogk.<<s. 



Note by Walter KiDD ... ]80 



The Cbos.s of S. Sophia. By F. C. Bureitt. Note by 



E. M. Antoniadi 181 



" CoMBTS and their Tails and the Gegenschein." 



By Feed. Or. Shaw. Note by The Reviewer ... 182 



Notes 183 



British Ornithological Notes. Conducted by Haebt F. 



Witherbt, P.Z.S., M.B.O.U 181- 



Notices of Books 185 



Books Received ... ... ... ... ... ... 186 



The Struggle for Existence in Sociology.— II. By 



J. Collier 187 



Microscopy. Conducted by M. I. Ceoss {Illustrated) ... 188 



Notes on Comets and Meteors. By W. F. Denning 190 

 The Face of the Sky for August. By W. Shackleton, 



p.b.a.8 191 



Chess Column. By C. D. LococK, b.a 191 



THE ANCESTRY OF THE ELEPHANT. 



By K. Lydekker. 



The two exi.stinof species of elephauts— Asiatic and the 

 Afriean — are not oiily the largest, but also two of the 

 most isolated amouo; the auinials of the present day. Tor 

 although evidently allied to more typical hoofed mammals, 

 like rhinoceroses, yet they are so different, that their 

 relationship is evidently remote. Elephants are not un- 

 frequently spoken of as " antediluvian " creatures ; and if 

 this term be regarded as equivalent to ancient, it is to a 

 great extent a true statement of the case, for elephants 

 and their progenitors, the mastodons, flourished during 

 e]>ochs wliich are old indeed in relation to human chrono- 

 logy, although modern fmin a geological standpoint. But 

 " antediluvian " implies in this sense, if we mistake not, 

 more than mere antiipiity, and indicates the primitive 

 structural characters of the animals to -which it is applied. 

 In certain respects an ele])hant is indeed decidedly primi- 

 tive, or generalised, although in other ways it is just as 

 specialised. In the possession of five toes" to each foot, as 

 well as in the structure of the wrist and ankle, elephants 

 are indeed truly primitive. Not improbably, in spite of 

 the fa('t that the o])posit(( view has been suggested, the 

 same is the case with regard to the peculiar coiiforuiation 



of their limbs, which difEer from those of all living 

 mammals. That is to say, in place of a marked angulation 

 at the junctions of their different segments, the bones of 

 each limb are placed almost vertically one above the other. 

 This structural peculiarity is, of cour.se, best displayed in 

 the skeleton, although the straightness of limb is very 

 perceptible externally, more esj;>ecially in the case of the 

 African species. The same feature characterises certain 

 extinct mammals, of the apjjroximate size of rhinoceroses ; 

 and from this it might be assumed that straight limbs 

 were common to all the earlier animals. Such, however, is 

 certainly not the case, the primitive carnivora, which come 

 very close to being the ancestral type of all the higher 

 mammals, having the limb-bones as much angulated as in 

 a dog. From this it has been suggested that straightness 

 of limb is a feature of comparatively modern origin, 

 developed for the purpose of carrying the immense weight 

 of an elephant. But, as mentioned later, the same feature 

 apparently occurs in the early ancestors of the elephant, 

 which were much smaller creatures ; and if such a type be 

 necessary in the case of an elephant, why is it not equally 

 essential in that of such a huge animal as the white 

 rhinoceros ? As regards limb-stiticture, elephants are 

 therefore apparently primitive. 



On the other hand the trunk, or proboscis, of an 

 elephant is a decidedly specialised organ, developed in 

 correlation with the great length of limb and shortness of 

 neck characteristic of elephants and mastodons. 



Equally peculiar and specialised is the dentition of 

 elephants, which consists of cheek-teeth, or grinders, and 

 tusks. The latter, which are most fully developed in the 

 males, and are preceded in infancy by a minute baby-pair, 

 are confined to the upper jaw, and correspond to the front 

 teeth of beavers, and not to the tusks of swine. Some of 

 the mastodons had only upper tusks, but in others a pair 

 was also developed in the lower jaw. 



Elephants, like tortoises, attain a prodigious age, 

 living to between one hundi-ed and fifty and two hundred 

 years, if not more. To attain this age, it is obvious 

 that they must have teeth calculated to last much longer 

 than those of other mammals, which liecome worn 

 out within twenty-five years, or much sooner. In 

 nature there are two wa\ s by which teeth may be made to 

 last longer than usual. They may either grow throughout 

 life, like the incisors of the Ijeaver, or their crowns may be 

 abnormally heightened. Further aid in the same direction 

 is afforded by retarding the appearance of the hinder 

 grinders, so that they shall not come into use till those in 

 front are nearly worn out ; this being merely an exaggera- 

 tion of what occurs in ourselves, where the wisdom-teeth 

 do not come into use until well on in mature life. 



In modern elephants both plans have been folli>wed ; the 

 first in the case of the tusks, and the second in that of the 

 cheek-teeth, or grinders. During life six pairs of grinders 

 are developed in each jaw of an elephant ; the first pair of 

 each series being small and almost functionless, while the 

 last is of enormous size, and does not make its appearance 

 till late in life, although the exact date of its coming into 

 use (as in the case of the other teeth) has yet to be 

 ascertained. Each lootli consists of a number of tall, thin, 

 transverse ]ilatcs. closely packed together, and coni)>rising 

 layers of different hardness, so that when worn the 

 grinding surface displays a series of low ridges, forming 

 an excellent millstone. The number of these plates 

 increases from the first to the last tooth in both species ; 

 but they are taller, thinner, and more numerous in the 

 Asiatic elephant and its relative the extinct mammoth, 

 than in their cousin the African elephant. As the teeth in the 

 fore part of the jaws are gradually worn away, their stumps 

 are pushed out by those next behind ; the whole series coming 



