. The testimony of the rocks; . t the present day, says a distinguishedfossil botanist, a warm and moist summer produces abroader annual layer than a cold and dry one, and if fos-sil plants exhibit such appearances as we refer in recentplants to a diversity of summers, then it is reasonable tosuppose that a similar diversity formerly prevailed. Thesame reasoning is of course as applicable to groups of an-nual layers as to single annual layers; and may we not ven-ture to infer from the almost invariable occurrence of suchgroups in the woods of this ancient system, that that ill-understood law o
. The testimony of the rocks; . t the present day, says a distinguishedfossil botanist, a warm and moist summer produces abroader annual layer than a cold and dry one, and if fos-sil plants exhibit such appearances as we refer in recentplants to a diversity of summers, then it is reasonable tosuppose that a similar diversity formerly prevailed. Thesame reasoning is of course as applicable to groups of an-nual layers as to single annual layers; and may we not ven-ture to infer from the almost invariable occurrence of suchgroups in the woods of this ancient system, that that ill-understood law of the weather which gives us in irregu- FOSSIL FLORAS OF SCOTLAND. 475 lar succession groups of colder and Avarmer seasons, andwhose operation, as Bacon tells us, was first remarked inthe provinces of the Netherlands, was as certainly in ex-istence during the ages of the Oolite as at the presenttime ? Twigs which exhibit the foliage of these ancient conifersseem to be less rare in our Scotch deposits than in those n)f Fig. CONIFERS ? England of the same age. My collection contains fossilsprigs, with the slim needle-like leaves attached, of what 476 ON THE LESS KNOWN seem to be from six to seven different species; and it isworthy of notice, that they resemble in the group ratherthe coniferae of the southern than those of the northernhemisphere. One sprig in my collection seems scarcelydistinguishable from that of the recent Altinga excelsa;another, from that of the recent Altinga Cunningliami,Lii^dley and Hutton figure in theii* fossil flora a mmutebranch of Dacrydium cupressinum^ in order to show hownearly the twigs of a large tree, from fifty to a hundredfeet high, may resemble some of the fossils referable toLycopodiaceae. More than one of the Oolitic twigs in my Fig. 131.
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