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 
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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 
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the unintermitting pressure of labor, and the numerous calls of our 
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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 mse pages, which may sometimes Sas in aie, retrospective.— 
— . 
- ae 
SCIENCE.- 7 ae 
Recherches sur les Poissons Fossiles. Texte et Planches. Lag. 
14. 1841. 
‘Histoire Naturelle des - Poissons d’Eau Douce de Europe Cen- 
trale. Tome I, sie contenant l’Embryologie des paleoan ss, 
Liv. 2, planches. i841. 
Etudes Critiques sur les s meeriaes Fossiles. Liv. ec plan. 
ches, contenant les Be be u Jura et de la Craie Se oda 
Monographies d’Ec rcaiieass, Vivans et Fossiles. Liv. 2, con- 
tenant les Scutelles; liv. 3, les Galerites et les Dysaster, par E. e 
Desor; liv. 4, PAnatomié du genre Echinus, par G. Valentin. 
Planches. 
aomeuclator Zoologicus, continens Nomina Systematica Gene- ; 
imalium, tam viventium a fossilium. Fasiculus 1, conm- 
” ae 
me pot a 
