CHAP. XTT. 



Age of, 409 



which thin out at Concepcion, and in central and 

 Northern Chile entirely disappear. This coincidence in 

 the distribution of the fossil wood and the living forests 

 may be quite accidental ; but I incline to take a diffe- 

 rent view of it; for, as the difference in climate, on 

 which* the presence of forests depends, is here obviously 

 in chief part due to the form of the land, and as the 

 Cordillera undoubtedly existed when the lignitiferous 

 beds were accumulating, I conceive it is not improbable 

 that the climate, during the lignitiferous period, varied 

 on different parts of the coast in a somewhat similar 

 manner as it now does. Looking to an earlier epoch, 

 when the strata of the Cordillera were depositing, there 

 were islands which even in the latitude of Northern 

 Chile, where now all is irreclaimably desert, supported 

 large coniferous forests. 



Seventy-nine species of fossil shells, in a tolerably 

 recognisable condition, from the coast of Chile and Peru, 

 are described in this volume, and in the Palasontological 

 part of M. d'Orbigny's c Voyage ' : if we put on one side 

 the twenty species exclusively found at Concepcion and 

 Chiloe, fifty-nine species from Navidad and the other 

 specified localities remain. Of these fifty-nine species 

 only an Artemis, a Mytilus, and Balanus, all from 

 Coquimbo, are (in the opinion of Mr. Sowerby, but not 

 in that of M. d'Orbigny) identical with living shells ; 

 and it would certainly require a better series of speci- 

 mens to render this conclusion certain. Only the 

 Turritella Ghihnsis from Huafo and Mocha, the T. 

 Patagonica and Venus meridionalis from Navidad, 

 come very near to recent South American shells, namely, 

 the two Turritellas to T. cingulata, and the Venus to 

 V. exalbida: some few other species come rather less 

 near ; and some few resemble forms in the older Euro- 

 pean tertiary deposits : none of the species resemble 



