ACKNOWLEDGMENTS TO CORRESPONDENTS, FRIENDS 

 AND STRANGERS. 



Remarks, — This method of acknowledgment has been adopt- 

 ed, because it is not always practicable to write letters, where 

 they might be reasonably expected ; and still more difficult is it 

 to prepare and insert in this Journal, notices of all the books, pamph- 

 lets, &ic., which are kindly presented, even in cases, where such no- 

 tices, critical or commendatory, would be appropriate ; for it is often 

 equally impossible to command the time requisite to frame them, or 

 even to read the works ; still, judicious remarks, from other hands, 

 would usually find both acceptance and insertion. 



In public, it is rarely proper to advert to personal concerns ; to 

 excuse, for instance, any apparent neglect of courtesy, by pleading 

 the unintermitting pressure of labor, and the numerous calls of our 

 fellow-men for information, advice, or assistance, in lines of duty, 

 with which they presume us to be acquainted. 



The apology, imphed in this remark, is drawn from us, that we may 

 not seem inattentive to the civilities of many respectable persons, au- 

 thors, editors, publishers, and others, both at home and abroad. It 

 is still our endeavor to reply to all letters which appear to require an 

 answer ; although, as a substitute, many acknowledgments are made 

 in these pages, which may sometimes be, in part, retrospective. — 

 Eds. 



SCIENCE. FOREIGN. 



Geologic des Gens du Monde, par K, C. de Leonhard de Hei- 

 delberg ; translated from the German by P, Grimblot and P. A. 

 Toulougan. Tome deuxieme. Paris, 1840. From the Author. 



Lethea Geognostica ; feuilles 13 and 14 of text, and Taf 13, 14, 

 16, 17, 18, 20, 21, 23 and 24. From the Author. 



Neues Jahrbuch fiir Mineralogie, &c. 1833, Heft. 1 and 6. 

 1838, Heft. 1, 4, 5, 6. From Messrs. Leonhard and Bronn. 



Several German Catalogues of Books, for sale by Nestler k, Mel- 

 le, Hamburg. From N. U M. 



Histoire Naturelle des Poissons d'Eau Douce de L' Europe Cen- 

 trale, par L. Agassiz. 1 Livraison, contenante les Salmones, folio, 

 with beautiful colored plates. From the Author. 



1 



