Probable Temperature during the Tertiary Period. 9 



and suffered itself to be led tractably to its place of con- 

 finement. * Would a rational being have acted like this 

 elephant? 



(To be continued.) 



Art. II. An Estimate of the probable Degrees of Temperature in 



Europe during the Tertiary Periods ; founded upon the Study 



of Fossil Shells. By M. G. P. Deshayes. Read to the French 



Academy, May 23. 1836. 



(From the Annales des Sciences Natnrelles.) 



Conchology, studied in a logical manner in its various 

 relations both to zoology and geology, may become a power- 

 ful means of bringing this latter science to perfection. It is 

 even allowable, in the present day, to anticipate the time when 

 conchology shall arrive at questions which relate to the ge- 

 neral physics of the terrestrial globe, and furnish us with the 

 necessary materials for their solution. 



Very numerous observations, repeated upon more than 

 eight thousand species of recent and fossil shells, and these, 

 again, multiplied upon more than sixty thousand individuals 

 of all regions, have enabled me to perceive important conse- 

 quences with regard to an approximate estimate of the tem- 

 peratures of the geological periods, concerning which man 

 cannot cite his historical annals, since he then had no exist- 

 ence upon the surface of the earth. 



If vegetables, as M. Arago has learnedly established in the 

 Annuaire du Bureau des Longitudes for 1834, can give the 

 mean temperatures of the historic period ; if the existence in 

 certain places of the vine, the palm, &c, are, to the skilful 

 naturalist, equivalent to thermometrical observations; I think 

 that animals also, and especially those which people the waters 

 of the ocean, may by their presence determine very nearly the 

 mean temperature of the place they inhabit. 



All marine animals are not adapted to indicate temperature 

 with the same precision : we must choose those which, pos- 

 sessed of but small powers of motion, cannot withdraw them- 

 selves periodically from the changes of the seasons, and are 

 obliged to sustain all their influence in the places which have 

 given them birth. The greatest number of the Mollusca and 

 Zoophytes answer to this description. 



To arrive at a knowledge of the temperatures of periods 

 antecedent to human existence, there is a chain of reasoning to 

 follow. We must first seek a starting point in existing na- 



* I shall have occasion to revert to this presently. 



