HOOKER READING FOSSIL PLANTS. 163 



Note on the Fossil Plants /ro/w Reading, 

 By J. D. Hooker, M.D., F.R.S., G.S. &c. 



The fossils collected by Mr. Prestwich may be all safely assvimed to 

 represent a vegetation differing in no important respect from that at 

 present inhabiting the north temperate zone ; but none of them afford 

 sufficient data for approximating to the generic affinities of the plants 

 to which they belonged*. After a careful collation of the specimens 

 with many existing plants comprised in the present floras of Eu- 

 rope, Northern Asia, and North America, I find no characters by 

 which they may be allied to those of one of these countries more than 

 another. Indeed I feel satisfied that similar forms of existing plants 

 might be associated by natural causes in any of these countries, but 

 that they would not necessarily belong to the same species, or even 

 genera, in all. 



The total absence of any remains indicative of a tropical vegetation 

 is important ; for although forms of foliage precisely similar to these 

 leaves from Reading are even more abundant in some tropical coun- 

 tries than in temperate ones, it is legitimate to suppose that had 

 the association resulted from a tropical vegetation, some more direct 

 evidences of their origin would have been forthcoming. 



I do not see that any objection can be urged to the assumption 

 that the climate of the epoch during which these plants flourished 

 was a temperate one, experiencing summer heat and winter cold, and 

 that it was not colder than that which now prevails in England ; 

 for the large size and membranous appearance of many of the leaves, 

 which, like those of the maple, lime, poplar, &c., are annual, indicate 

 some duration of summer warmth ; and the leaf-buds (figured 24, 25, 

 and 26) are similar to those of various trees which lie dormant for a 

 considerable period of the year. It may also be remarked that there 

 are no appearances of articulations at the base of the leaves, such as 

 would suggest the probability of any of them belonging to Legumi- 

 nous or other plants with compound foliage, which in the present dis- 

 tribution of vegetation in the north temperate zone indicate a warmer 

 mean temperature than England now enjoys. 



The absence of any traces of Coniferousf or other gymnospermous 

 vegetation, and of ferns, is a point of considerable interest ; for in all 



* These important observations by Dr. Hooker on the probable temperature 

 of this period were made perfectly independently of my own, for, when they were 

 written, he had not read the previous part of this paper, published in the last 

 Part of the Journal, p. 136, nor have I, until after the printing of the above, had 

 any communication with him on the subject of these plants. The conclusions, 

 therefore, to which we have both arrived, upon independent evidence, respecting 

 the apparently moderate climate prevailing here at this old Eocene period, and 

 the absence of those tropical forms which abound in the succeeding London Clay 

 period, furnish strong corroborative proof of the truth of this singular fact. In my 

 former paper on the Thanet Sands I had arrived at the same conclusion respect- 

 ing the temperature of the sea in which this oldest of our Tertiary deposits was 

 accumulated (Quart. Journ. vol. viii. p. 260). — [J. P., Jun., April 15, 1854.] 



t Coniferous wood, however, is present in the Woolwich series of East Kent, 

 and a Fern at Counter Hill. — [J. P., Jun.] 



