. On the natural history and classification of birds . s very dissi-milar. If, for instance, we look to the two typicaldivisions of vertebrated animals — as quadrupeds andbirds — and compare them with the corresponding groupsof the Annulosa, or insects, we immediately perceive thatthere may be an analogy, but that there cannot existany possible affinity. But how stands the case whenthe groups to be compared are smaller ? Let us look tothe circle of the Pariana to illustrate this question. (66.) The typical genera, as seen in the annexed dia-gram, are Parus and Sylvicola ; the subgenera Par us
. On the natural history and classification of birds . s very dissi-milar. If, for instance, we look to the two typicaldivisions of vertebrated animals — as quadrupeds andbirds — and compare them with the corresponding groupsof the Annulosa, or insects, we immediately perceive thatthere may be an analogy, but that there cannot existany possible affinity. But how stands the case whenthe groups to be compared are smaller ? Let us look tothe circle of the Pariana to illustrate this question. (66.) The typical genera, as seen in the annexed dia-gram, are Parus and Sylvicola ; the subgenera Par us andEgithalus in one, and Vermivora and Sylvicola in theother, are consequently the external or typical , in support of our opinion, that what are to betermed analogies in larger groups, insensibly changetheir character, and blend into close affinities in smallergroups, we appeal to this circle. Is not the resem- TYPICAL GROUPS CONNECTED. 57 Egithalua Mniotilta \l EgithinaSYLVrCOLA cb PARUSSyhicola^p A oj Parus Zosterops ^V \p Hylophilus. blance (we will neither term it analogy nor affinity)between Egithalus and Vermivora fully as strong asthat between Mniotilta and Egithina ? We should cer-tainly say it is: again, supposing neither Mniotiltanor Egithina had been discovered, and we had nosuspicion that such forms existed, in what mannershould we suppose that the genera Varus and Sylvicolawere united by direct affinity ? In such a case, weshould undoubtedly point to Vermivora, as passing intoParus by means of Egithalus. So close, indeed, is theresemblance between the two, that nothing but a slightdifference in their wings and feet serves to separatethem. Can then a resemblance, which, in such a case,is sufficiently strong to constitute an affinity, be termeda mere analogy ? we think not: on the contrary, webelieve, that in proportion as we contract our views,and investigate the nature of the typical or externalgroups in small circles, we shall find they follow eacho
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