Mr. LyelPs Address. 405 



long period, sufficient at least to allow of tlie extinction of many 

 large species of quadrupeds. The family of the armadillos is now 

 exclusively confined to South America and here we have from the 

 same country the Megatherium, and two other gigantic represen- 

 tatives of the same family. So in the Camelidse, South America is 

 the sole province where the genus Auchenia or Llama occurs in a 

 living state, and now a much larger extinct species of Llama is dis- 

 covered. Lastly, among the rodents, the largest in stature now 

 living is the Capybara, which frequents the rivers and swamps of 

 South America and is of the size of a hog. Mr. Darwin now 

 brings home from the same continent the bones of a fossil rodent 

 not inferior in dimensions to the rhinoceros. 



These facts elucidate a general law previously deduced from the 

 relations ascertained to exist between the recent and extinct qua- 

 drupeds of Australia ; for you are aware that to the westward of 

 Sydney on the Macquarie River, the bones of a large fossil kan- 

 garoo and other lost marsupial species have been met with in the 

 ossiferous breccias of caves and fissures. 



A cavern has lately been examined at Yealm Bridge, six miles 

 south-east from Plymouth, by one of our members, Lieut. Col. 

 Mudge, R.E., from whose account it appears that the bones of hy- 

 senas are very numerous there. They are associated with those of 

 the elephant, rhinoceros, horse, and other animals usually found in 

 caves. The number of fossil Carnivora, such as the hyaena, wolf, fox, 

 and bear, which have now been met with in districts of cavernous 

 limestone in Great Britain, is so great that we are the more struck 

 with the rarity and general absence of such remains in surrounding 

 and intervening districts, over which the same beasts of prey must 

 have ranged. The Pachydermata, as the elephant, rhinoceros, and 

 hippopotamus, are often discovered in ancient alluvial or fluviatile 

 deposits ; but had there been no caves and fissures we should 

 scarcely have obtained any information respecting the existence of 

 lions, tigers, hyaenas, and other beasts of prey which inhabited the 

 country at the same period. 



The remains of at least two distinct Saurian animals have been 

 discovered by Dr. Riley and Mr. Samuel Stutchbury, in the dolo- 

 mitic conglomerate of Durdham Down near Bristol. They are 

 allied to the Iguana and Monitor, but the teeth, vertebrae, and other 

 bones exhibit characters by which they are seen to be generically 

 distinct from all existing reptiles. They are particularly deserving 

 of your attention as occurring in the bottom of the magnesian lime- 

 stone formation, the oldest strata in which the bones of reptiles have 

 as yet been found in Great Britain. The most ancient examples 

 of fossil reptiles known on the continent of Europe occur also in 

 the zechstein of Germany, a formation of about the same age. 



I alluded last year to a memoir of Sir Philip Egerton's, in which 

 he pointed out some peculiarities in the structure of the cervical 

 vertebrae of the Ichthyosaurus. He has now proved that in all the 

 species of this genus there are three accessory bones, which he pro- 

 poses to call, from their shape and position, sub vertebral wedge 



