Vice-President’s Address. 229 
This series is well shown in the South Wales Coal Field, 
where the Lower Pennant Rocks, and in Somerset the New 
Rock and Vobster Series, belong to it. 
In the coal field of the Potteries the dividing line between 
the Middle and Upper Coal-Measures has been drawn at a 
thin band of Spirorbis Limestone. There seems. to be no 
break between the two series, and the division between them 
is an arbitrary one. 
In the rocks a few yards above the Spirorbis Limestone, 
Dr Hind has met with Neur. heterophylla, Brongt., and Neur. 
gigantea, Sternb., along with Sphenophyllum emarginatum, 
Brongt. The two first species are characteristic of Middle 
and Lower Coal-Measures, and the last mentioned of Upper 
Coal-Measure rocks. Some other species were collected 
from the same bed, but were too imperfect to admit of a 
satisfactory determination. 
The rocks in the region of this Spirorbis Limestone are 
clearly of a ‘‘ Transition Series” nature, but in the Potteries 
Coal Field they appear to be so feebly developed that for 
practical purposes they do not need, and, in fact, can scarcely 
be, separated from the overlying Upper Coal-Measures with 
which they have been classed. But it is desirable to mention 
these facts here. 
In the same coal field there appear to be indications 
of a Transition Series between the Lower and Middle 
Coal-Measures, but they are so slightly developed as to 
demand no further notice than the mere mention of the 
circumstance. 
It is unnecessary to particularly mention the plants which 
characterise this series, for its character is simply an 
admixture of Middle and Upper Coal-Measure species. 
This is shown in the column devoted to the flora of the 
Transition Series, which is given in the “ Vertical Distribu- 
tion Tables” at the end of this address, 
VII. Upper CoAL-MEASURES. 
The outstanding plants by which the Upper Coal- 
Measures are distinguished from all the other horizons are 
