26 NOTICES OF BOOKS. 



recent formations. In the little volumes before us, each deals with 

 his own special subject, and produces a work of more importance 

 than one would look for in a popular series of three-shilling volumes. 



Although the title of Renault's volume is general, it really deals 

 with some of the chief forms of plant-life found in Carboniferous 

 rocks. Chapters are devoted to an enquiry into the conditions 

 under which plants are preserved in the rocks, and the methods of 

 preparing them for minute examination; and after expounding the 

 various forms with which he deals, he enquires into the value 

 of these plants in determining the nature of the climate when 

 they lived, the age of the strata in which they are imbedded, and 

 the light they throw on the theory of evolution. 



Renault has done so much for these early plants, that it is im- 

 possible to read his work without adding to one's knowledge ; and 

 yet one is everywhere reminded how dangerous it is to be governed 

 by liistoric views in any investigation. The interpretations of 

 Calamudeiulron and SiniUaria by the illustrious Brongniart, singularly 

 cautious and philosophic considering the materials at his disposal, 

 have been completely modified by the abundant and varied 

 material which has been examined in more recent years. Yet 

 Renault adheres to the old views, and employs great ingenuity in 

 defending them. In the Carboniferous Flora there are, as every 

 one allows, representatives of three great divisions of the vascular 

 cryptogams — the Horsetails, Club-mosses, and Ferns. The Horse- 

 tails are represented by large, jointed and branching plants with 

 whorls of leaves and long slender corms. One set of stems in- 

 creased by a secondary exogenous growth of scalariform tissue, and 

 these Renault separates as Gymnosperms, though the fruits of the 

 two groups present no differences that can be detected. The 

 figures he gives of the fruits of his cryptogamic Annularia and 

 his gymnospermous Arthropitus and Cal(imode)idron might be trans- 

 posed without injury. Of course he calls the contents of the one 

 microspores and of the other pollen, but this is a necessity of his 

 interpretation, and would not be accepted by any unbiassed 

 student of the cones. The triple spores correspond, he believes, 

 with the pollen-grains discovered in the pollen-chamber of several 

 gymnospermous fruits, and so confirm the view he takes. 



The same difficulty presents itself in his treatment of Siyillana. 

 The secondary growth in the stem is contrasted with the structure 

 of an imperfect stem of Lppidodendron, and the latter genus is 

 classed among the Lycopodiacetr., while the former is reckoned a gym- 

 nosperm. The more perfect specimens of the stems of both genera 

 show that histologically and structurally both stems agree, and the 

 as yot rare indications of fruit in Sitjilhiria present the same kind 

 of spores as are better known in Lepidodendron. No doubt the 

 stems of these paheozoic E(jui.sct(icc<c and Lijcopoduiccir were more 

 Jiighly organized than the living representatives, in accordance with 

 their arboreal habit and longer duration. 



Renault's revision of the Carboniferous Ferns is less exhaustive, 

 but is clear and instructive. More also might have been made of 

 the remarkable series of gynniospermous fruits, the exposition of 



