104 Des Moulins on the genera Unio and Anodonta. 
Art. XI—Des Moulins’ General Considerations on Restricting 
the number of Species of the Genera Unio and Anodonta ; trans- 
lated from the French, by Purr H. Nicxuin, A. M. 
Prefatory Remarks by the Translator. 
Te paper of Mr. Charles des Moulins, now offered in an Eng- 
lish translation, possesses merits of a very high order. It criti- 
cises without acrimony, and praises without flattery ; it is scientific 
without pedantry, and philosophical without obscurity. It is 
imbued throughout with the enlightened spirit of catholic Chris- 
tianity, which does honor to the writer, and is a favorable symp- 
tom of the moral condition of the scientific world. 
Mr. Des Moulins was the predecessor of Dr. Graleloup in the 
presidency of the Linnean Society of Bordeaux, and is doubt- 
less a naturalist of a high order. On the presentation of the 2nd~ 
volume of Mr. Isaac Lea’s Conchological Observations to the 
Linnean Society, Mr. Des Moulins requested of the Society to 
be charged with the ‘ Rapport,’ on account of his familiar know- 
ledge of the English language, acquired during a long residence 
in Great Britain. In a letter to Mr. Lea he observes, “as I felt 
obliged to speak my thoughts plainly in the rapport, I ventured 
to give an explanation of the principles and method on which I 
would rely, for an enucleation of the true species from amidst the 
mere forms and differences of sex and age, and in short from all 
sorts of varieties. This theoretical part of my paper, the Lin- 
nan Society have judged fit to be printed in their transactions.” 
“As for the second part of my work, which was plainly the Re- 
port on your volume, it was not admissible in such a kind of re- 
view as our transactions, where original writings only can be ad- 
mitted, and it is not worth my sending a manuscript copy. Let 
me only tell you that I gave a numerical account of the species 
of each genus you described, that I criticised your changing the 
Lamarckian generic name Fridina* for Platiris, and the specific 
one of Iridina rostrata, Rang, for celestis, while it remains evi- 
* If ‘Tridina’ had been retained for the genus, it would have been necessary to 
strike from Lamarck’s generic description the following phrase, “ per longitudinem 
tuberculosus, subcrenatus ; tuberculi inequalibus, crebris 3” because the Iridina 
rubens and its fellows, now forming Mr. Lea’s subgenus Spatha, do not fulfil that 
cardinal condition: it was therefore manifestly proper to adopt a new name for the 
