Auo. 4, 1882.] 



KNOWLEDGE 



150 



^^|I V^ AN !LJ,iL£TRATCD ^J^' 



- >^ MAGAZINE ofSlIENCE'^ 



YfORDED-EXAC TlYPESCRlBLu J 



. PIAINLY 



LONDOX.- FRIDAY, AUGUST 4, 1882. 



COSTEKTS OF No. -10. 



Fonnd Links. By Dr. Andrew 

 Wilson, F.R.S.E., F.L.S 



The Relation of Eiercise to Brain- 

 work 



The Amateur Electrician. Electric 

 Measurement. — I 



Home Cures for Poisong 



Thought-Reading. Bt the Editor . : 



English Seaside HealtB-Re.^orts (iciM 

 an illmtrative map) . By Alfred 

 •• riland, M.E.C.S., F.R.M.C.S. 





A Procession of Irebergs {ilhu 



Weather Charts for the Week" 



Chaldean Antiquities at the 1a 

 (illattrated) 



CORBESPONDEXCE : Are Toads 

 sonousP— A.rtistic Perceptio 

 Animals, &c 



Answers to Correspondents 



Our Paradox Column 



Soienco and Art Uossip 



Our Mathematical Column 



Our Chess Column 



Our Whist Column 



FOUND LTNKS. 



By Dr. Andrew Wilson, F.R.S.E., F.L.S. 



{Concluding Paper.) 



NOW, as regards the past history of the Mammalia, 

 there exists abundance of evidence to show that 

 many extinct quadrupeds stand in relation to these 

 existing orders in the light of " intermediate forms " or 

 "links." The recent researches of Professor Marsh 

 amongst the American fossil mammals have been fraught 

 with literally surprising results in this latter direction. 

 Prior, however, to Marsh's discoveries, there were not 

 wanting facts wliich pointed to the conclusion that the 

 demands of evolution for links between the existing orders 

 of quadrupeds would not be made in vain. Take for 

 example the single order of the Whales. Ko more circum- 

 scribed and apparently distinct group of animals exists, 

 yet their relationship to other orders of quadrupeds is no 

 mere matter of conjecture, but one of proof. 'There is a 

 fossil whale known as Z<-ngJodon, found in Tertiary deposits, 

 and so named from the peculiar double-nature of the 

 molar teeth. Whales with sucli teeth are unknown to-day, 

 and when the allinities of Zenglodon are examined, they 

 are seen to point to a clear connection with the Seals and 

 Walruses, belonging as wo have seen to the Cai'-iivora. 

 It would thus seem as if the natural idea that the Seals 

 •and Wiiales were near relations was founded on fact ; and 

 fossil whales certainly tend to bridge over tlie gulf betwixt 

 the two groups. IJut this case, powerfully as it argues in 

 favour of the connected series of animals which evolution 

 requires, is by no means .solitarj*. We have long known, 

 for example, of the Anoplothcrium, nn extinct quadruped, 

 which presents in itself a curious mixture of tlie cliaracters 

 of Pigs and Ruminant animals, i.e., those that "chew the 

 cud," and comparative anatomists will tell us that the jiigs 

 and hippopotamus group themselves show, in many 

 respects, an approximation to the Ruminants. Or to take 

 yet another example from Cuvierian times, we find in the 

 PalaioiJiei-ium aa animal which links the Tapirs to the 



Horses, and which shows a combination of characters that 

 amply satisfies the evolutionist of its "intermediate" 

 nature. 



But the more recent discoveries of ISIarsh throw the fore- 

 going cases into the shade in respect of the mass of material 

 which that indefatigable paheontologist has accumulated. 

 Thus we have been forced to constitute a whole series of 

 new orders for the reception of the forms Professor Marsh 

 has unearthed. What, for instance, shall we say of the 

 extinct D'moccrns and its neighbours? These Luge 

 elephantine animals united in themselves the characters of 

 Elephants, and of odd-toed " hoofed " ((Uadrupeds. With 

 limb-bones like those of l^lephants, Dinoceras possessed 

 teeth that exhibited a combination of the characters of 

 carnivorous animals with those of "hoofed " forms. More 

 extraordinary still were the Tillodonts from the Eocene 

 rocks of the United States. Here are combined the 

 features of hoofed quadrupeds [unjulata), Carniforous 

 animals, and Rodents. With a skull like that of a Bear, 

 Tillotherium possessed front teeth exactly resembling those 

 of the Rodents, or "Gnawers," and which appear to have 

 combined to grow throughout the life of the animal, whilst 

 the grinding-teeth were those of a hoofed animal. So, also, 

 another group of extinct animals, of which Toxodon is the 

 chief, presents us with a combination of characters 

 mingling those of the " Hoofed ' forms with those of 

 Rodents and Edentates — such as the Sloths, Auteaters, Ac. 



As a final example of the curious " links " between 

 existing forms, which may be found amongst the treasures 

 disclosed by scientific inquiry, the curious " Flying 

 Lemurs" (UaleopUhecvs) may be mentioned. These 

 animals are found in the Eastern Archipelago, and re- 

 semble Squirrels in appearance. A curious fold of skin 

 stretches from the sides of the neck to the fore limbs, and 

 between hind-limbs and tail. The body is thus fringed, as 

 it were, by a broad fold of skin, and although, unlike the 

 bats, the flying lemurs do not possess true powers of flight, 

 the skin-folds serve as a kind of parachute, supporting 

 these animals in the air, as they take their flying haps 

 from tree to tree. In their internal anatomy these animals 

 exhibit transitional features, and on the whole may be 

 regarded as linking the Insectivora with the higher group 

 of the Primates in which Man and Apes ai-e included. 

 Whilst it seems tolerably clear that the Bats themselves 

 are merely Insectivorous animals which have undergone the 

 modifications fitting them for true flight 



Sudi is a brief and meagre outline of the result of an 

 incursion into the province of geology as that science 

 relates itself to the past history of living forms. In con- 

 cluding the series of papers on " Found Links," I may 

 perhaps be permitted to add that the design of these 

 articles will have been fully served, if they may in any 

 way stimulate the personal inquiries of my readers into 

 the great study of modern times, namely, that of ascer- 

 taining how the univtrse of life has In-en modified and 

 evolved. Such a study is fraught with profit in more 

 ways than one. The search after evidence in favour of or 

 against Kvolution necessitates an amount of inquiry which 

 is certain to strew the observer's pathway with curious 

 facts concerning every department of life science. Furtlier- 

 more, the main question at ii-sue is one whidi in reality 

 underlies all our conceptions of life, and of tlie order of 

 nature. It is the question which tiie best and wisest of 

 mankind have ever asked and inquired of tiiemselves— the 

 How, Wiiy, and Whence of this world and iU belongings. 

 Hapjiy indeed are they who, in the spirit of earnest truth- 

 seekers, are permitted to engage in the work of discovering 

 new facts and phases of the wondrous story of creation, 

 which Nature is ever inviting us to peruso. 



