E. A. Neu-ell Arber— Plants from Kent Coal-field. 99 



other palseobotanists, and they agree with me in this conclusion. 

 I believe them to be members of the genus Pterophyllum, one of the 

 earliest types of leaf belonging to members of this alliance, appearing 

 first of all in Carboniferous times. They may be compared with 

 Pterophyllum hlechnoides , Sandb./ from the Stephanian of the Black 

 !Forest. Other species of this genus are known from the Stephanian 

 and Permian of other parts of Germany, and especially from France. 

 Fronds of this type are also abundant in the earlier Mesozoic rocks. 



The occurrence of a Pterophyllum, even although the fi'onds are too 

 fragmentaiy to warrant specific determination, in beds containing 

 a typical Transition Coal-measure flora, is a quite unique experience 

 in England, and, so far as I am aware, in the Westphalian rocks of 

 Europe. Such rare cases illustrate the first slow incomings of the 

 Cycadophyta, a group which reached its maximum during the Mesozoic 

 period. The transition from the Palaeophytic to the Mesophytic type 

 of flora was probably a perfectly gradual one. The Mesophytic types 

 begin to appear towards the close of the Palaeozoic period. They 

 come in very gradually, but become more numerous as we pass up 

 through the Permian. It is not until Triassic times that they occupy 

 the position of a dominant group. The rare occurrence of such a type 

 of frond as Pterophyllum, one of the earliest known Cycadophytean 

 fronds in the Stephanian and Permian, is thus of interest, and it is 

 now satisfactory to find that this genus can be traced back as far as 

 the Westphalian. 



In this connexion it is interesting to recall the fact that a single 

 twig of Walchia imbricata, Schimper, a plant of obvious Coniferous 

 affinity, was described some years ago by Dr. Kidston ^ from the 

 Upper Coal-measures of the Hamstead Colliery, Great Parr, near 

 Eirmingham. Here, again, we have one of the earliest evidences of 

 the incoming of another great Mesozoic group, the Coniferse. 



EXPLANATION OF PLATE V. 



The numbers refer to the Carboniferous Plant Collection of the Sedgwick 

 Museum, Cambridge. 



ElG. 1. Dictyocalamites Burri, sp. et gen. nov., showing a node and part of 



an internode which has reticulated ridges. No. 2259. From the 



Barfreston boring, Kent, at 2,559 feet, x f . 

 ,, 2. Pterophyllum sp. A portion of a leaf showing the stout rachis to 



which fragments of leaflets are attached. No. 2220. From the 



Barfreston boring, Kent, at 1,834 feet. x f. 

 ,, 3. Dictyocalamites Burri. Another portion of an internode, enlarged, 



showing the reticulating ridges and (?) scars of adventitious roots. 



No. 2224. From the Barfreston boring at 2,559 feet, x f . 

 ,, 4. Pterophyllum sp. Another fragment of a leaf in which the pinnules 



are somewhat more perfect. No. 2221. From the Barfreston boring 



at 1,834 feet, x 3. 

 ,, 5. Dictyocalamites Burri. A portion of another internode, showing the 



ridges and a (?) scar of an adventitious root. No. 2224. From the 



Barfreston boring at 2,559 feet, x f . 



^ Sandberger, Verhandl. Natunoissen. Verein Karlsruhe, vol. i, p. 30, 1864. 

 ^ Kidston, Trans. Eoy. Soc. Edinb., vol. xxxv, pt. vi, p. 324, pi. i, fig. 9, 1891. 



