Revieics — Prof. A, Gaiidry — On Evolution. 33 



species." He points out the various lines of ideas which prevailed 

 amongst the earlier vrriters down to the period of Cuvier and 

 D'Orbigny, when a series of stratified deposits had been recognized, 

 but each with its fauna and flora was believed to be quite distinct and 

 separate from the one before, or the one which followed after. 



In Chapter II. he shows that the idea of their relationship to each 

 other is quite compatible with the teachings of Geology ; that the 

 S3'stem of appearances and universal destructions, although not defi- 

 cient in grandeur, has given place to more philosophical views ; and 

 that we are now aware that the hard lines of separation between the 

 geological formations were only local phenomena ; and that if life was 

 interrupted at one point, it was continued at another. 



The ten chapters which follow give us an account of the Primary 

 formations and their fossils. Then the Ccelenterata, the Echinoder- 

 mata, the Brachiopoda, the Gasteropoda and Conchifera, the Cephalo- 

 poda, the Artliropoda, the first Fishes and the first Eeptiles, have 

 each a chapter devoted to them, accompanied by numerous and 

 excellent figures. 



" There cannot," writes Prof. Gaudry, " be a doubt as to the 

 former connexion between the life-forms of the Cambrian and Silu- 

 rian, and between these and the Devonian and Carboniferous; and 

 these and the Permian, and again between the Permian and those we 

 call Secondary." 



M. Briart has observed, " All the epochs are connected one with 

 another, not by beings preserved in an exceptional manner, but by 

 entire faunas, and floras." " The pi'imary Foraminifera were singu- 

 larly like the pi'esent ones ; several of the genera have continued 

 from Carboniferous times to the present day. Not- only do they 

 graduate from one into another, but we have difficulty in establish- 

 ing lines of demarcation between the families, whether we take 

 their texture or their mode of grouping as the basis of classification. 



" The same thing occurs with the Ccelenterata as with the Fora- 

 minifera. Formerly they were ari'anged according to their mode of 

 grouping, but it was soon apparent that this mode offered but poorly- 

 marked distinctions. 



" At the present day we class their families according to their 

 intimate structure, and yet we see transitions between them. Still 

 we find passages between the Tnhidaia, the Tabtdata and the Rugosa, 

 and to the well-septated Madreporaria. Nor is it easy to establish 

 a marked separation between the ancient and recent Eydrozoa. 



" Notwithstanding their apparent diversity, the greater part of 

 the Crinoidea can be referred to one common type. The study of 

 the Sea Urchins has not yet established any transition between the 

 PalceoechinidcB and the Neoecliinidce ; nevertheless it is possible to 

 conceive that by the union and atrophy of one portion of iheir test, 

 the transition may have been effected. 



"The researches of Mr. Thos. Davidson, F.R.S., have shown us 

 that the Brachiopoda pass from one species to another. It is not 

 always easy to establish barriers between the genera of different 

 families. The Lingida, Cranice, Discince, Terehratida, and RIdju- 



DECADE III. — TOL. I. NO. I. 3 



