I 



1 80 Metamorphosis of Crabs. 



unite two countries, where a common language can best express 

 the progress of the general mind. There is much solicitude here, 

 on the subject of the geology of your country ; and you must per- 

 ceive by the increase of natural history literature, how welcome 

 every new fact will be to us, in any of its branches, from your 

 side of the water. The appearance of your Journal, will, of course, 

 be hailed here by all, and will be indulgently judged by your 

 numerous friends. We are aware how arduous a task you have 

 undertaken, and that but few, at present, will find leisure to as- 

 sist you. But if you adopt a popular course, you will acquire 

 the confidence of those able to strengthen you, and after a few 

 months there will be no lack of useful correspondents and friends 

 to your undertaking. This has been the career of all the pe- 

 riodicals of this country, which are distinguished for intelligence. 



In a country like America, abounding with objects of natural 

 history, the opportunities for indulging in neology, are very great : 

 it is the vice of science. Your conchologists will tire of it, by and 

 by, as others have done, and molluscous architecture, — a subor- 

 dinate branch, — will become simplified and intelligible. They 

 will be glad, as others have been, to condense their tedious lists, 

 and shut them up into some prominent point, like those nice lit- 

 tle nests of boxes we see sometimes. This is already going on 

 in more important branches, and will be extensively done, ere 

 long, in others. Mr. Thompson, author of the * Zoological Re- 

 searches and Illustrations in Natural History,' is carrying reform 

 into the crustaceas, and is showing that many of this class under- 

 go changes, as they advance to maturity, quite as curious as those 

 of insects. He has succeeded in hatching the eggs of the com- 

 mon crab, and the young, instead of being like their papa and 

 mamma, turn out to be the zoea, which had been raised to the 

 rank of a genus of the modern systems by Bosc, who discovered 

 it in the ocean. When we shall be able to extend this tadpoli- 

 zation to the rest of the decapodous Crustacea, a great reforma- 

 tion will be effected in the rotten boroughs of natural history. 

 Mr. Thompson remarks of the metamorphosis of the young crabs, 

 that at the tender period, before any change, they are * essen- 

 tially and purely natatory animals, and, no doubt, possessed of 

 corresponding habits, swimming about freely, and without inter- 

 mission, in search of appropriate food. In their perfect state, 

 the greater number can no longer avail themselves of the power 



