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, &c., 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 Jabor, 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, implied 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. 
Recherches sur les Poissons Fossiles. Texte et Planches. Liv. 
14. 1841. 
Histoire Naturelle des Poissons d’Eau Douce de |’Europe Cen- 
trale. Tome I, texte, contenant Embryologie des Salmones. 
Liv. 2, planches. i841. 
Etudes Critiques sur les Mollusques Fossiles. Liv. 2, avec plan 
ches, contenant les Myes du Jura et de Ja Craie Suisses. 1842. 
Monographies d’Echinodermes, Vivans et Fossiles. Liv. 2, con- 
tenant les Scutelles; liv. 3, les Galerites et les Dysaster, par E. 
Desor; liv. 4, ?Anatomié du genre Echinus, par G. Valentin. 
Planches. 
Nomenclator Zoologicus, continens Nomina Systematica Gene- 
rum Animalium, tam viventium quam fossilium. Fasiculus 1, con- 
1 
