LEAF-BEDS OF MULL, IN SCOTLAND. 
247 
feet. Below this sand are forty-five beds of alternating lig¬ 
nite and clay. No shells or bones of mammalia, and no in¬ 
sect, with the exception of one fragment of a beetle {Bupres- 
tis) ; in a word, no organic remains, except plants, have as 
yet been found. These plants occur in fourteen of the beds— 
namely, in two of the clays, and the rest in the lignites. 
One of the beds is a perfect mat of the debris of a coniferous 
tree, called by Heer Sequoia Couttsim^ intermixed with leaves 
of ferns. The same Sequoia (before mentioned as a Hemp¬ 
stead fossil, p. 246) is spread through all parts of the forma¬ 
tion, its cones, and seeds, and branches of every age being 
preserved. It is a species supplying a link between S. 
Langsdorjii (see Fig. 153, p. 238) and /SI Sternhergi^ the wide¬ 
ly spread fossil representatives of the two living trees S, sem- 
pervirens and S, gigcmtea (or Wellingtonia), both now con¬ 
fined to California. Another bed is full of the large rhizomes 
of ferns, while two others are rich in dicotyledonous leaves. 
In all. Professor Heer enumerates forty-nine species of plants, 
twenty of which are common to the Miocene beds of the 
Continent, a majority of them being characteristic of the 
Lower Miocene. The new species, also of Bovey, are allied 
to plants of the older Miocene deposits of Switzerland, Ger¬ 
many, and other Continental countries. The grape-stones of 
two species of vine occur in the clays, and leaves of the fig 
and seeds of a water-lily. The oak and laurel have supplied 
many leaves. Of the triple-nerved laurels several are refer¬ 
red to Cinnamomum. There are leaves also of a palm of 
which the genus is not determined. Leaves also of protea- 
ceous forms, like some of the Continental fossils before men¬ 
tioned, occur, and ferns like the well-known Lastrcea stiriaca 
(Fig. 154, p. 238), displaying at Bovey, as in Switzerland, its 
fructification. 
The croziers of some of the young ferns are very perfect, 
and were at first mistaken by collectors for shells of the ge¬ 
nus Blanorhis. On the whole, the vegetation of Bovey im¬ 
plies the existence of a sub-tropical climate in Devonshire, in 
the Lower Miocene period. 
Scotland : Isle of Mull. —In the sea-cliffs forming the head¬ 
land of Ardtun, on the west coast of Mull, in the Hebrides, 
several bands of tertiary strata containing leaves of dicoty¬ 
ledonous plants were discovered in 1851 by the Duke of Ar¬ 
gyll.* From his description it appears that there are three 
leafJbeds, varying in thickness from to 5^ feet, which are 
interstratified with volcanic tuff* and trap, the whole mass 
being about 130 feet in thickness. A sheet of basalt 40 feet 
* Quart. Geol. Journal, 1851, p. 19. 
