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VII. A Monograph of the British Species of the Genus Choleva, ` 
By William Spence, Esq. F.L.S. . 
Read December 19, 1809. 
Iv must have struck the Entomologist who has attended to the 
philosophy of his science, that Linné, in his institution of ento- 
mological genera, has been guided by a rule very different from 
that which he has followed in the sister science Botany. In the 
latter, his genera are numerous. When a tribe of plants was 
marked by a peculiar habit, he seldom scrupled to erect it into a 
distinct genus, even though obliged in some of the natural families 
to adopt very slight and evanescent generic characters. And where 
a plant decidedly differed in its inflorescence from every known 
genus, he rarely allowed similarity in habit to be any bar to its 
separation into a new one. In Entomology, on the contrary, his 
genera are extremely few; and of these a great proportion are 
clearly natural families: while at the same time, under more li- 
mited genera are not seldom included insects diametrically at 
variance with the generic character. But if, in Botany, the Cru- 
. ciate, Papilionacee, &c. were to be regarded as families composed 
of several genera; so, on every principle of analogy, ought the 
Linnean entomological genera Scarabeus, Curculio, Cerambyx, 
Musca, &c., each of which includes tribes of insects of the most 
opposite ceconomy, and most distinct and peculiar habit. And if 
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