604 
SUPPLEMENTARY NOTES. 
P. 198. In the summer of 1836, Mr. Murchison discovered 
at Ludlow, in the sandy slate rocks that form the upper members 
of the Silurian System, a very curious Bed, from one to five or 
six inches thick, almost entirely composed of dislocated bones, 
teeth, and scales of Fishes, intermixed with numerous small 
coprolites. In all these circumstances of its organic remains, this 
bed resembles the stratum called the bone bed, at the bottom of 
the Lias on the banks of the Severn, near Aust Passage, and 
near Watchet, which is similarly loaded with bones, teeth, and 
coprolites derived from Fishes, and with dislocated bones of 
Reptiles. This Ludlow Bone bed affords the first example yet 
noticed, of remains which prove the abundant existence of Fishes 
in that early period of the Transition series, when the upper strata 
of the Silurian system were deposited. 
The occurrence of teeth, scales, bones, and coprolites derived 
from Fishes, in strata of the Carboniferous system, is noticed at 
p. 275, and p. 276, Note. 
P. 208. The opinion that the colour of the skin of the Chame¬ 
leon was varied by the varied intensity of its inspirations, has been 
recently disproved by Dr. Milne Edwards, who has shewn that 
this variation is produced by changes in the disposition of layers 
of differently coloured membranous pigments, placed one above 
another under the cuticle, and capable of such changes that one 
may sometimes hide the other. Hence it follows that the conjec¬ 
ture of Cuvier is not verified, which attributed to the Plesiosaurus 
the possibility of its having been able to change the colour of its 
skin, in consequence of the resemblance in the structure of its 
ribs to that of the ribs of the Chameleon. 
See Penny Cyclopaedia, Vol. VI. p. 474, et seq. 
P. 214. A remarkable exemplification of the exquisite Power 
of the human hand has been communicated to me by Mr. James 
Gardener, of Regent Street, London, from whom I learn that he 
has with his own hand, aided by the sense of touch alone, and 
with his eyes shut, ruled parallel lines, which being examined with 
a micrometer, were found to be at the exact distance of - 5 -r^ of 
an inch from one another. With his unarmed eye he cannot 
