October 31, 1901 J 



NA TURE 



65: 



developed in purely pelagic cetaceans like the killer, 

 while in littoral or fluviatile forms, such as the narwhal, 

 the white whale and the Japanese porpoise, it is either 

 ■*' small or wanting. It is, further, noticeable that cetaceans 

 with pointed muzzles (of which Zcm^lodon is one) nearly 

 always have a larger back-fin than those in which the 

 muzzle is short and rounded. In the whalebone bones, 

 among which the dorsal fin is either small or wanting, 

 its function may be discharged by the keel on the middle 

 of the upper jaw, or, owing to corporeal bulk, no such 

 function is required at all. 



If, then, we are right in regarding Zcuglodon as a 

 pelagic cetacean, it is evident that it could not have 

 been completely armoured, but that such armour as it 

 retained was merely a survival from a fully armoured 

 non-pelagic ancestor. For it is almost impossible to 

 believe that the ancestral cetacean was not invested in a 

 complete panoply, at least on the dorsal region. 



The whole argument is tersely summed up as follows 

 by Dr. O. Abel [Bci/r. Pal. Oster.-Ung.., vol. xiii. pt. 4, 

 1901), to whom naturalists are indebted for these 

 interesting researches. 



In their earliest stage of development the toothed 

 whales were fully armoured. The object of the armour 

 was as a defence against enemies, such as sharks, such 

 an armour being also very valuable to animals e.xposed 

 to the force of a strong surf on rocky shores. As the 

 creatures took more and niore to an aquatic life, the 

 acquisition of greater speed would be of greater value to 

 them, and this would be accomplished by diminishing 

 the specific gravity and friction of the body, the shorten- 

 ing of the e.xtremities and the development of a caudal 

 fin to serve as the sole instrument of locomotion, 

 t Accordingly the armour would very soon be lost by 

 Ihe pelagic cetaceans in order to diminish friction and 

 ighten the specific gravity. Only among certain types, 

 which diverged at an early epoch from the ancestral 

 stock and took to a fluviatile or estuarine life, did 

 vestiges of the armour persist, while the dorsal fin 

 remained undeveloped {Ncop/tocnoia). That in this 

 form, as well as in the closely allied true porpoises 

 {P/iOLiieiia), we have the most primitive type of living 

 toothed whales, is confirmed by the nature of their denti- 

 tion, as well as by the circumstance that in this group 

 alone the premaxilla is toothed. The relation of the 

 interparietal to the parietals is likewise confirmatory of 

 the antiquity of the porpoises. 



As many of our readers are aware, Zciiglodo)i differs 

 from modern cetaceans by the characters of its teeth, 

 those of the lateral series being double-rooted and having 

 compressed and serrated crowns, distantly recalling 

 those of the leopard-seal. Between Zciiglodon and the 

 shark-toothed dolphins ySqualodon) the gap is very 

 great, 'but'still one which might readily be bridged were 

 the'missing links forthcoming ; and as it is the molars 

 of the one type seem derivable from those of the other. 

 I In Squalodon the molars alone retain the double-rooted 

 character o{ Zciiglodon, and a transition from the former, 

 in respect of tooth characters, to the modern dolphins 

 and porpoises is afforded by Saurodelpliis, of the 

 Argentine Pliocene, in which the roots of the teeth, 

 although single, are elongated antero-posteriorly and 

 thus display clear evidence of their original duality.' 

 By Dr. Abel, Saiirodelphis is indeed regarded as occupy-' 

 ing the middle position between Squalodon and the 

 modern dolphins ; but the porpoises are considered to 

 forni a side branch which diverged from the, main stem 

 at an earlier date than the appearance of the genus first 

 named. 



In conclusion, it may be mentioned that modern investi- 

 gations' tend to connect the ancestral toothed whales 

 with the Garnivora, and in no wise support Sir William 

 Flower's favourite idea that these cetaceans trace their 

 descent from early Ungulates. R. L. 



NO. 1670, VOL. 64] 



TIBET AND CHINESE TURKESTAN} 



T^'HE geographical area illustrated by Captain Deasy's 

 ^ book lies in one of the most remote and, at the same 

 time, one of the most interesting regions (regarded 

 politically) in the whole continent of Asia. 



British India (represented by Kashmir) lies south and 

 west of it ; to the north, north-east and east stretch the 

 shadowy outlines of the " new dominion " of China and 

 the lofty uplands of Tibet ; Russia looms large to the 

 north-west ; and a long thin slice of Afghanistan reaching 

 out an arm eastwards nearly touches it on the western 

 border. It is an area which bristles with the physical 

 difficulties presented by a vast array of gigantic mountain 

 chains interspersed with flat spaces of desolate upland 

 and salt marsh, and it is an area which those high 

 authorities who regulate international boundaries will 

 sooner or later find it necessary to discuss in close detail ; 

 for hereabouts exists one of the nebulous corners of the 

 Empire. Boundary commissions have come and gone, 

 but they have still left undecided the question how far 

 China extends south, or Kashmir north ; nor can anyone 

 give final shape to Russia's line of boundary where she 

 leaves Afghanistan and spreads eastward towards China. 

 Consequently Captain Deasy's geographical work, and 

 the interesting book in which it is described, possess a 

 value which can only be regarded as unique. It is only 

 by the light of his excellent map that any conclusions can 

 be drawn as to the physical nature of this rugged no 

 man's land, and only by the light of his description of it 

 can any value be assigned to its apparently desolate hills 

 and* valleys. It is no small achievement for a cavalry 

 officer to carry the principles of scouting on scientific 

 geographical lines into such a field of difficulty and deso- 

 lation as is presented by the buttressed spurs of the Kuen 

 Lun and the Muztagh ranges. 



Captain Deasy has set a most excellent example to 

 aspiring travellers in remote regions — an example which 

 has been lately emphasised strongly by the methods of 

 the great traveller Sven Hedin — in the careful prepara- 

 tions which he made for the scientific prosecution of his 

 work. He is not merely an observer. He has proved 

 himself to be an advanced geographical surveyor. He 

 first armed himself with all available data on which to 

 base his exploration, and then attached himself to the 

 best of all possible schools of instruction in order to 

 learn how to make the best use of it. The result is a 

 map which is probably quite accurate enough to take its 

 place as the standard geographical reference for all that 

 part of High Asia with which it deals, and which must 

 be regarded as the most important result of his combined 

 literary and field efforts. His observations were all 

 worked out by the professional computers of the Indian 

 Survey, and the results are tabulated and a record made 

 of their value, in the appendix to his book ; so that the 

 indefinite haze which usually envelops similar records 

 by less careful workmen is absent in Captain Deasy's 

 work, and we know precisely what to make of it. The 

 book, which embraces the narrative of his travels (illus- 

 trated by an excellent series of photographs), is written 

 with the traditional modesty of a soldier, and gives a 

 faithful and graphic account of the extraordinary diffi- 

 culties which beset the travellers in the Tibetan border- 

 land. There is no occasion to exaggerate these difficul- 

 ties, or to draw on . the imagmation for thrilling 

 episodes and situations. They are formidable enough 

 to tax all the resources of ability and determination 

 which the best of explorers may have at his command. 

 If Captain Deasy's own description of them hardly does 

 justice to the extraordinary obstructiveness of the ugly 

 passes of the gigantic Tibetan ranges, his illustrations 

 at least do not fail to make it plain. It is almost 



1 " Tibet and Chinese' Turkestan." By Capti 

 (London : T. Fisher Unwin, 1901.) Price 2i.y. 



Deasy. Pp. xvi + 420. 



