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Rh and in a numerous race it may be said to occupy the whole surface, rendering the hemelytra very similar to the tegmina of Orthoptera. On the other hand, the transparent portion often encroaches on the region of the other, to a greater or less extent, and in Coreus, Tingis, Aphis, &c., the whole is nearly of a uniform membranous consistency. This want of uniformity has occasioned difference of opinion among authors respecting the position, affinities, and constitution of the Hemipterous order. Linnæus confounded it with the Orthoptera; others, in order to avoid the impropriety of associating gnawing insects with suctorial ones, effected their separation; and thinking it also improper to unite such as have half membranous upper wings with those in which they are wholly coriaceous, formed two separate orders under the names Hemiptera and Homoptera. This was done by De Geer, in which he was followed by Dr. Leach and Mr. MacLeay. Although the differences in the texture of the wings are certainly important, and it has the appearance of inconsistency not to take them into account in an arrangement where they are professedly assumed as indicating primary sections, more especially when they are connected, as in this instance, with corresponding differences in economy, it has notwithstanding been generally thought inexpedient to admit the separation alluded to. The transition from a corneous to a membranous texture, is certainly so gradual, that it would be difficult to fix where the line of demarcation should be drawn; all the species agree in the