Metamorphom of Crahfs. 179 



cal facts are sought by many, with as much avidity as gold was 

 looked for in the fifteenth century. 



I offer these notices and reflections for the consideration of 

 those who are occupied in the important investigation of the 

 origin and progress of the civihzation of mankind. In another 

 letter, I propose to speak of the extraordinary remains of Pa- 

 lenque, the Palmira of Mexico. I have the honour to remain, 

 sir, with the most unfeigned respect, A Mexican. 



ON THE METAMORPHOSIS OF THE YOUNG OF THE 

 COMMON CRAB. 



Extract from the Letter of a correspondent, dated London, June 18th, 183L 



" The prodigious accession of new objects in natural history, 

 especially from the animal kingdom, has placed great tempta- 

 tions in the way, both of young and old naturalists. Like those 

 orators who contend for victory, and not for truth, there arc too 

 many individuals who are inditFerent to the means by which they 

 acquire their trophies. To have brought forward a new genus 

 or a new species, and then cry, ' exegi monumcntum,' if even 

 the immortality does not promise a longer life than ' green peas,' 

 has not been beneath the ambition of some minds, who can see in 

 classification and nomenclature, the great end of all knowledge. 

 Science, which has been somewhat fatigued by naturalists of 

 this class, is now recovering from the dead weight they had be- 

 come to it ; but, like the tail of the tadpole, in its progress to 

 maturity, they are becoming gradually absorbed. The voice of 

 experience is at length listened to ; we are already indifferent 

 to conclusions, come they from what quarter they may, which 

 are not obviously deduced from facts ; and any man who pre- 

 tends to belong to the multitudinous host of naturalists, which has 

 sprung up in Europe, — as under the protection of Minerva, men 

 were formerly produced from teeth, sown by Cadmus, in Bceotia, — 

 must be very cautious — if he means to survive — how he skirmishes 

 on his own account. These reflections, which grow out of the past 

 and passing conduct of natural history with us here, may not be 

 inapplicable to the United States, where a great deal of good sense, 

 has to contend with inexperience, and no doubt with sciolism. 



That natural history should flourish with you, in the United 

 States, is sincerely to be desired ; an additional bond will thus 



