422 MR. J. S. GARDNER ON ALNUS RICHARDSONI. 
moment the real nature of the supposed cells is admitted, the 
reference of the fossil to the Proteacew becomes difficult; and I 
can now see no resemblance in it either to fruits of Petrophila 
or Zsopogon ; and though itis hardly necessary to notice the fact, 
no leaves of either of these genera, so far as I know, have ever 
been recognized among European fossil plants. I have equally 
sought in vain for any analogous fruits among the true Conifer@ 
and the Cycads ; Larix, Dammara, and Cunninghamia seem to 
approach it most nearly, but they possess no detailed structure 
in common. In like manner, its reference to Sequoia 18 incom- 
prehensible; for besides the fact that the scales are fen times 
more numerous, there are absolutely no characters to justify it. 
I am not yet able to give a list of the fossil species of Alnus 
from other deposits. Only one other occurs, so far as I know: 
in England, at Bournemouth ; and this possesses very small cones, 
which were shed clustered together. Cones of nearly equal dimen- 
sions have been obtained from the Tertiaries of Koumi in Eubea, 
from Aix in Provence, and from Antrim; and other species from 
Austria and Switzerland, which are compared with the existing 
A. cordatum and A. orientalis. Our London-Clay species is pum x 
bably the oldest of which the fruit is known. It is an interesting 
circumstance that it is entirely confined to that part of the for- 
mation met with at Swale Cliff, Herne Bay, and which is below 
the horizon of the Sheppey fruits; and its absence from the later 
zones, considered with many other facts, tends to show that the 
maximum temperature was not reached till late, instead of at the 
commencement of the London-Clay period. 
For the benefit of paleontologists who may consult this paper, 
it will be well to add that there are fourteen existing species of 
Alnus, which range through Europe, Central and Northern Asia, 
North America, and the Andes, with one outlying species in Africa. 
They thus inhabit temperate countries, and the association of 
their fruits in large quantities with the Nipa and other tropical 
vegetation of Sheppey would be as incongruous as it is untrue. 
The cones have often been taken to Folkestone for sale, and 
imbedded in Gault. 
DESCRIPTION OF PLATE XXXI. 
Fig. 1. Elongate form of Alnus Richardsoni. 
Fig. 2. Average form, showing cavities left by removal of decayed scales. 
Fig. 3. Example with scales partially remaining. 
