Ch. XIY.] lignites of bovey TRACEY. 241 



The lignite is of bad quality for economical purposes, as there is 

 a great admixture in it of iron pyrites, and it emits a sulphurous 

 odour, but it has been successfully applied to the baking of pottery, 

 for which some of the fine clays are well adapted. Mr. Pengelly has 

 confirmed Sir H. De la Beche's opinion that much of the upper por- 

 tion of this old lacustrine formation has been removed by denu- 

 dation.* 



At the surface is a dense covering of clay and gravel with angular 

 stones probably of the Post-pliocene period, for in the clay are three 

 species of willow and the dwarf birch, Betula nana, indicating a cli- 

 mate colder than that of Devonshire at the present day. 



Below this are Lower Miocene strata about 300 feet in thickness, in 

 the upper part of which are twenty-six beds of lignite, clay, and sand, 

 at their base a ferruginous quartzose sand, varying in thickness from 

 two to twenty-seven feet. Below this sand are forty-five beds of 

 alternating lignite and clay. No shells or bones of mammalia, and 

 no insect with the exception of one fragment of a beetle (Buprestis) ; 

 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 Couttsiw, 

 intermixed with leaves of ferns. The same Sequoia is spread through 

 all parts of the formation, its cones, and seeds, and branches of every 

 age being preserved. It is a species supplying a link between 

 S. Langsdorjii (see figs. 201, 202 p. 263) and S. Sternbergi, the 

 widely-spread fossil representatives of the two living trees S. sempervi- 

 rens and S. gigantea (or Wellingtonia), both confined in the living 

 creation to California. Another bed is full of the large rhizomes of 

 'ferns, while two others are rich in dicotyledonous leaves. In all Pro- 

 fessor Heer enumerates forty-nine species of plants, twenty of which 

 are common to the Miocene bed 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 Switzer- 

 land, Germany, and other continental countries. The grape-stones of 

 two species of vine occur in the clays, and the leaves of three species 

 of fig, seeds also supposed to belong to three new species of Nyssa, or 

 Tupelo tree, a genus now common in the swamps of South Carolina 

 and Florida, two species of Annona, and a new water-lily. The oak 

 and laurel have supplied many leaves. Of the triple-nerved laurels 

 three or four are referred to Cinnamomum. There is a palm also, of 

 which the genus is not determined. Among the Proteaceae arc men- 

 tioned Bryandr tides Hakecefolia (fig. 198), D. Banksiwfolia, and 

 another. Among the ferns is the well-known continental fossil Las- 

 trcea stiriaca (fig. 203, p. 264), displaying at Bovey as in Switzerland 

 its fructification. 



Phil. Trans., 1863. Paper by W. Pengelly, F.R.S., and Dr. Oswald Heer. 

 16 



