CONIFERS IN THE SECONDARY SERIES. 367 



these modifications of the existing Family of Coniferas date 

 their commencement from that very ancient period, when 

 the Carboniferous strata of the Transition formation were 

 deposited. 



Fragments of trunks of Coniferous wood, and occasion- 

 ally leaves and cones occur through all stages of the Oolite 

 formation, from the Lias to the Portland stone. On the up- 

 per surface of the Portland stone, we find the remains of an 

 ancient forest, in which are preserved large prostrate silici- 

 fied stumps of Coniferas, having their roots still fixed in the 

 black vegetable mould in which they grew. Fragments of 

 coniferous wood are also frequent throughout the Wealden 

 and Greensand formations, and occur occasionally in 

 Chalk.* 



It appears that the Coniferae are common to fossiliferous 

 strata of all periods ; they are least abundant in the Transi- 

 tion series, more numerous in the Secondary, and most fre- 

 quent in the Tertiary series. Hence we learn that there has 

 been no time since the commencement of terrestrial veseta- 

 tion on the surface of our Globe, in which large Coniferous 

 trees did not exist ; but our present evidence is insufficient, 

 to ascertain with accuracy the proportions they bore to the 



(PI. 56a. Fig. 6. a) the longitudinal section has the characters of Araucaria. 

 (PI. 56a. Fig. 3, 5.) So also those Coniferse of the great Coal formation of 

 Edinburgh and Newcastle, which exhibit the structure of Araucaria in 

 tlieir longitudinal section, have no distinct concentric layers ; whilst in the 

 fossil Coniferas from the New Holland and Nova Scotia Coalfield, both lon- 

 gitudinal and transverse sections agree with those of the recent tribe of 

 Pinus. 



Mr. Witham also observes that the Coniferae of the Coal formation, and 

 mountain limestone group, have few and slight appearances of the con- 

 centric lines, by which the annual layers of the wood are separated, which 

 is also frequently the case with the Trees of our present tropical re- 

 gions, and from this circumstance conjectures that, at the epochs of these 

 formations, the changes of season, as to temperature at least were not 

 abrupt. 



* There is in the Oxford Museum a fragment of silicified coniferous wood, 

 perforated by Teredines, found by Rev, Dr. Faussett, in a chalk flint at Lower 

 liardrcs, near Canterburv. 



