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XVII. Of the Insect called Oisrros by the Ancients, and of the 
true Species intended by them under this Appellation : in reply 
to the Observations of W. S. MacLeay, Esq., and the French 
Naturalists. To which is added, A Description of a new Species 
of CurEnEBRA. By Bracy Clark, F.L.S., and Foreign Mem- 
ber of the Royal Academy of Sciences of Paris. 
Read November 19, 1826, and February 20, 1827. 
Ix the 14th volume of the Transactions of the Linnean Society, 
is a communication written by my friend W. S. MacLeay, Esq., 
intended to prove that the fiy, intitled Oistros by the ancients, 
was not the insect so named by Linnæus, but that it probably 
belonged to the present Linnean genus Tabanus. 
Being of a contrary opinion, I am led once more to address 
this learned Society, to lay before them the grounds on which it 
is founded, that naturalists may not incautiously and too hastily 
adopt the above conclusion, and that they may avoid the con- 
fusion which change of names and counter changes always pro- 
duce in science. I am also led to this undertaking in order to 
vindicate Linnaeus himself, our great master, and such distin- 
guished naturalists as Vallisneri and Reaumur, with whose 
. views on this subject I wholly concur. Nor is the justification 
of myself wanting as a motive to induce me to re-examine the 
subject, having formerly sent to this Society a dissertation of 
some extent on the genus Œstrus, unfolding some curious dis- 
coveries 
