452 SUPPLEMENTARY NOTES. 



must have rivalled the Hippopotamus in dimensions, bu<t which, 

 has the dentition of an animal of the Rodent Order; and it is 

 worthy of remark, that the largest living species of that order, the 

 Capybara, is peculiar to South America. Mr. Darwin has also 

 collected fragments of a small Rodent, closely allied to the Agouti; 

 and the remains of an Ungulate quadruped, of the size of a Camel; 

 and which forms a link between the aberrant group of Rumi- 

 nantia to which the Camels and Llamas belong, and the order 

 Pachydermata." 



P. 154, 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 hone 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 copro- 

 lites 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 Silu- 

 rian system were deposited. 



The occurrence of teeth, scales, bones, and coprolites derived 

 from Fishes, in strata orthe Carboniferous system, is noticed at p. 

 209, and p. 210, Note. 



P. 102. 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 shown 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 

 tlie possibility of its having been able to change the colour of it's 



