EXISTING SPECIFIC FORMS ABUNDANT. 97 



and under what circumstances, such a current was produced. 

 But in the present state of our knowledge, all that can be 

 legitimately inferred from the Diluvium, or, as it is now more 

 generally called, Drift, is, that many portions of the northern 

 nations of Europe and America were then under the sea, and 

 that a strong current, producing certain mechanical results, set 

 over them. 



Connected with the Drift is the history of Ossiferous 

 Caverns, of which specimens singly exist at Kirkdale in 

 Yorkshire, Gailenruth in Franconia, and other places. They 

 occur in the calcareous strata, as the great caverns generally 

 do, but have in all instances been naturally closed up, till the 

 recent period of their discovery. The floors are covered with 

 what appears to be a bed of the diluvial clay, over which rests 

 a crust of stalagmite, the result of the droppings from the roof 

 since the time when the clay bed was laid down. In the in- 

 stances above specified, and several others, there have been 

 found, under the clay bed, assemblages of the bones of animals, 

 of many various kinds. At Kirkdale, for example, the re- 

 mains of twenty-four species were ascertained namely, pigeon, 

 lark, raven, duck, and partridge ; mouse, water-rat, rabbit, 

 hare, hippopotamus, rhinoceros, elephant, weasel, fox, wolf, 

 deer (three species), ox, horse, bear, tiger, hyena. From many 

 of the bones of the gentler of these animals being found in a 

 broken state, it is supposed that the cave was a haunt of 

 hyenas and other predaceous creatures, by which the smaller 

 ones were here consumed. This must have been at a time 

 antecedent to the floodings which produced the drift clay, since 

 the bones are covered by a bed of that formation. It is im- 

 possible not to see here a very natural series of incidents. 

 First, the cave is frequented by wild beasts, who make it a 

 kind of charnel-house. Then, submerged in the current which 

 has been spoken of, it receives a clay flooring from the waters 

 containing that matter in suspension. Finally, raised from the 

 water, but with no mouth to the open air, it remains unin- 

 truded on for a long series of ages, during which the clay 

 flooring receives a new calcareous covering from the droppings 

 of the roof. 



Our attention is next drawn to the erratic blocks or boulders, 

 which in many parts of the earth are thickly strewn over the 

 surface, particularly in the north of Europe. Some of these 

 blocks are many tons in weight, yet are clearly ascertained to 

 have belonged originally to situations at a great distance. 



