ol 
Translated by Philip H. Nicklin. 107 
sion in its pages. The important question, “what is species ?” 
which he asks but does not answer, seems to present itself at the 
beginning of every arrangement; and that naturalist would be 
canonized who should answer it in a manner acceptable to all. 
The definition given by Milne Edwards in his Elémens de 
Zoologie, seems to be sufficient for the purpose of arrangement : 
“On donne le nom d’espéce a la réunion des individus qui se re- 
produisent entre eux avec les mémes propriétés essentielles.” 
od 
Philadelphia, April 10, 1841, 
General Considerations on the Reform which ought to take place 
in restricting the number of Species of the genera Unio and 
Anodonta. Presented to the Linnean Society of Bordeaux, at 
its sitting of the 5th of July, 1839, on the occasion of the pub- 
lication of Mr. Isaac Lea’s second volume of Conchological 
Observations. By Cu. Des Movurins, Member of the Linnean 
Society of Bordeaux, &c. 
Gentlemen—An able designer had arranged, in a hundred ad- 
joining compartments, a hundred figures, of which each one dif- 
fered so little in appearance from its neighbor, as to be indistin- 
guishable at the first glance. The first was the figure of the 
pollo Belvidere, the last was that of a frog. This curious com- 
parison shadows forth a relation little flattering to the physical 
man, but of much importance in a philosophical* point of view, 
in the sense now attached to this word. — It is the graphic repre- 
Sentation of the celebrated maxim of Linneus, Natura non facit 
saltum— Nature makes no leaps.’ a 
Bat really, gentlemen, what is nature? Nature, ac ing to 
the notion of Linnaeus, in the opinion of Christians, in truth is 
nothing else than the whole of those laws, or material order, which 
od imposed on physical things when he created. them. Now 
gentlemen, this saying of Linnzeus is admirable, it is profound, it 
is true in the material order, the object at once of the study and 
teaching of the Professor of Upsal ; and the more worthy it is of 
our respect, the greater is the necessity of adding to ita commen- 
tary, restraining its scope within the bounds contemplated by its 
immortal author. 
_ ™ The use of this word often appears to me grammatically absurd ; sometimes, 
instead of it, we ought to say physiological, but oftener ‘metaphysical ; but unfor- 
tunately the latter frightens children, even children of all ages. 
