CuAi'. VI. Affinities and Genealogy. 165 



group of fishes, as lowly organised as the laiicelet; and from 

 these the Ganoids, and other fishes like the Lepidosiren, must 

 have been developed. TVom such fish a very small advance 

 would carry us on to the Amphibians. We have seen that birds 

 and reptiles were once intimately connected together ; and the 

 Monotremata now connect mammals with reptiles in a slight 

 degree. But no one can at present say by what line of descent 

 the three higher and related classes, namely, mammals, birds, 

 and reptiles, were derived from the two lower vertebrate classes, 

 namely, amphibians and fishes. In the class of mammals the 

 steps are not diiBoult to conceive which led from the ancient 

 Monotremata to the ancient Marsupials ; and from these to the 

 early progenitors of the placental mammals. We may thus 

 ascend to the Lemuridse ; and the interval is not very wide from 

 these to the SimiadiB. The Simiadse then branched off into two 

 great stems, the Now World and Old World monkeys ; and from 

 the latter, at a remote period, Man, the wonder and glory of the 

 Universe, proceeded. 



Thus we have given to man a pedigree of prodigious length, but 

 not, it may be said, of noble quality. The world, it has often 

 been remarked, appears as if it had long been preparing for the 

 advent of man : and this, in one sense is strictly true, for he 

 owes his birth to a long line of progenitors. If any single link 

 in this chain had never existeii, man would not have been exactly 

 what he now is. Unless we wilfully close our eyes, we may, with 

 our present knowledge, approximately recognise our parentage ; 

 nor need we feel ashamed of it. The most humble organism is 

 something much higher than the inorganic dust under our feet ; 

 and no one with an unbiassed mind can study any living 

 creature, however humble, without being struck with enthusiasm 

 at its marvellous structure and properties. 



the existing tidal Ascidians. Many cess or function, would not, when 

 instances of such periodic processes once gained, be liable to change; 

 might be given, as the gestation of consequently it might be thus trans- 

 mammals, the duration of fevers, &c. mitted through almost any number 

 The hatching of eggs affords also a of generations. But if the function 

 good example, for, according to Mr. changed, the period would have to 

 Bartlett (' Land and Water,' Jan. 7, change, and would be apt to change 

 1871), the eggs of the pigeon are almost abruptly by a whole weelv. 

 iiatched in two weeks ; those of the This conclusion, if sound, is highly 

 "owl in three ; those of the duck in remarkable ; for the period of gesta- 

 'bur; those of the goose in five; tion in each mammal, and the 

 »nd those of the ostrich in seven hatching of each bird's eggs, and 

 weeks. As far as we can judge, a many other vital processes, thna 

 recurrent period, if approximately betray to us the primordial bir'h> 

 0/ the right duration for any pro- place of these animals. 



