i 



534 



IMBEDDING OF OEGANIC EEMAINS 



[Ch. XLVI, 



m 



In the 



lacustrine peat of the same locality^ the elytra of beetles are 



uncommon 



ally, and in the silt of our estuaries, the relics of this class 

 of the animal kingdom are rare. In the blue clay of very 

 modern origin of Lewes levels, Dr. Mantell has found the 

 Indusia, or cases of the larvae of Phryganea, in abundance 

 with minute shells belonging to the genera Planorbis 

 Limnea, &c., adhering to them.^ 



When speaking- of the mip-rations of insects. T nniTifa/l mi4- 



immense number 



from 



them 



circumstances, to sink to the bottom before thej 

 devoured by insectivorous animals or decomposed. 



Of land and freshwater 



As the bodies of several 



down 



by the river inundation which attended an earthquake in 



floods 



may 



mud may stifle many 



alligators and other reptiles which frequent lakes and the 

 deltas of rivers in tropical climates. Thousands of frogs 

 were found leaping about among the wreck, carried into the 

 sea by the inundations in Morayshire, in 1829 ;t and it is 

 evident that whenever a sea-cliff is undermined, or land is 

 swept by other violent causes into the sea, land reptiles may 

 be carried in. ' , ■ 



Of birds. — We might have anticipated that the imbedding 

 of the remains of birds in new strata would be of very rare 

 occurrence, for their powers of flight insure them against 

 perishing by numerous casualties to which quadrupeds are 

 exposed during floods ; and if they chance to be drowned, or 

 to die when swimming on the water, it will scarcely ever 

 happen that they will be submerged so as to become preserved 

 in sedimentary deposits. In consequence of the hollow 

 tubular structure of their bones and the quantity of their 

 feathers they are extremely light in proportion to their 



* Trans. Geol. Soc, vol, iii. part i. 

 p. 201, second series. 



t Sir T. D. Lauder's Accoiint, 2nd ed., 



p. 312. 



t 



f 



