THE EXTINCT LAKE OF BOVEY TRACEY. 
191 
out," toward the east, that is to say with increase of distance from 
Dartmoor ; thus, the lowest and thickest bed of Sand — distinctly 
seen from end to end of the Pit — was in the most westerly section 
133 inches thick, 460 feet farther eastward it measured no more 
than 19 inches, and 220 feet still farther east it had dwindled to 
10 inches, and this attenuation was very gradual and continuous. 
Again, three of the beds of the first Section — two of Sand and 
one of Clay — had "thinned out" before reaching the second 
Section ; and another bed of Clay was in like manner lost in the 
third and most easterly Section. 
Once more, the Clays were much finer and purer in the eastern 
part of the Basin than in the western. 
Further, some of the Sand beds — notably the thick one, men- 
tioned already more than once — contained crystals of Felspar, 
some of them an inch in length, and with comparatively few traces 
of abrasion. 
In short, there seems no reason to doubt that all the detrital 
beds were derived from the Dartmoor granite. All the materials 
composing them were derivable from the granite, and some of 
them could not have been furnished by any other rock in the dis- 
trict ; the thinning and " thinning out " showed distinctly that the 
transportation was from the west, that is from the immediately 
adjacent Dartmoor. 
Two beds of Clay and thirteen of Lignite were found to be 
fossiliferous, and the ultimate collection consisted of a very large 
number of specimens containing a considerable variety of species 
— all, with the exception of one elytron of a beetle, the remains 
of Plants. The collection was submitted to the Rev. Professor 
Oswald Heer, m.d., the eminent palseo-phytologist of Zurich, whose 
determinations and inferences were printed by the Royal Society 
of London, preceded by a history of the investigation and a 
description of the deposits, prepared by myself. {Phil. Trans, for 
1862, clii. 1019-1086.) The two Papers were at once reprinted, 
with " Prefatory Remarks," chiefly historical, and published as a 
Monograph, entitled " On the Lignite Formation of Bovey Tracey, 
Devonshire." 
According to Professor Heer, the Plants represented by the 
relics found in the Lignite Formation belonged to 50 distinct species, 
viz. : — 3 Fungi, 4 Ferns, 1 Conifer, 4 Monocotyledons, 31 Dicoty- 
