322 Bibliogrnpkical Notices. 



features and inhabitants is now so often attempted, _ INIr. Mackie's 

 treatment of the subject to which he has devoted this Httle book is 

 careful and judicious. It is a sul)ject, in one sense, far removed from 

 actual observation ; for the first animals and plants that lived upon 

 the earth have so long passed away, that we know not whether the 

 oldest fossils that we meet with be indeed the remains of the oldest 

 creatures. Taking for granted, however, that the lowest fossiliferous 

 rocks now known represent the earliest sediments of life-bearing 

 waters — that their modes of deposit indicate the nature of th.e coasts 

 and sea-bottoms of primeval geography— that their materials point 

 to the character of the adjacent land — that their obscure fossils, 

 often mere marks and holes, can be made to give a full and certain 

 meaning, — we may with advantage study the author's sketches of 

 the primeval lands and " of the first forms of the organized creatures 

 which inhabited it — the forms of those abundant tribes whose 

 offices played the first important part in the past conditions of our 

 planet, and whose remains are characteristic of our lowermost rock- 

 masses." 



For those who know not on what principles a geologist Avorks in 

 mixing his colours, stretching his canvas, handling his pencil, and 

 bringing up the features of the forgotten past with nature's tints, 

 Mr. Mackie provides some clever chapters on "the nature of 

 fossils," " the value of fossils," "the order of the rocks," "what we 

 knoAv of the earth's crust," and on " the rock-strata and their teach- 

 ings." The reader will here find most of the chief principles of 

 geological science briefly but clearly stated,— especially the very 

 necessary doctrine that IS^ature's operations of to-day illustrate the 

 results of natural agencies, atmospheric, terrestrial, and aqueous, in 

 past times. Thus "we see in the microscopic structure of many of 

 those finer silicious rocks which are composed of an aggregation of 

 the solid cases of Infusoria, and of limestones composed of nearly 

 equally minute Entomostraca and Foraminifera, the slowly formed 

 life-elaborated produce of the tranquil lake, or of the profound abysses 

 of the deep. Our ponds and inland seas give us the key to the one, 

 the soundings for the great Atlantic telegraph that to tlie other. 

 The silent language of the past, in which these facts are written, 

 appears at first strange and unintelligible, as the tongue of our Saxon 

 forefathers does to us now. But as the languages of the ancient 

 peoples are interpreted by our own and by those of contemporary 

 nations, so the events and changes of the past conditions of our 

 planet can be understood only by comparison Avith the phsenomena 

 going on around us." 



The outlines of the first dry lands, and the remnants of them now 

 licre and there to be found — how their Avearing-away gave rise to 

 sediments which, as hardened quartzose schists and slates, now yield 

 scanty evidence of primeval life (sea-AVorms, Zoophytes, and a few 

 Crustaceans perhaps) — hoAV the Avind and rain and sunshine played 

 on the long, flat, sandy ooze of those old shores, — these are the 

 pohits and features Avhich take ])roniincnce in tlie geological sketch 

 before us. With a facile touch the artist has coloured in the dreamy 



