The Zoologist — February, 1867. 571 



Prof. Westwood exhibited a highly magnified drawing of a monstrous individual 

 of Pieris Pyrrha, a Brazilian butterfly, from the collection of Mr. Hewitson, of which 

 the two wings on the left side of the body and the fore wing and costa of the hind 

 wing on the right side were coloured as in the male (being white on the upper surface 

 with a black tip to the fore wiugs, thus resembling Pieris Brassicae), whilst the 

 remainder of the right hind wing was coloured as iu the female, thus resembling oue 

 of the Heliconiida?. Prof. Westwood remarked that such a specimen and such a 

 species afforded ground for some comment on the relationship of those mimetic 

 animals which had recently attracted so much attentiou, and had afforded Mr. Bates 

 materials fur a remarkable and elaborate paper in the 'Transactions of the Linneau 

 Society.' Prof. Westwood, in the first place, considered that every species of animal 

 (except in the instances noticed below) was, so far as its habits and economy were 

 concerned, as independent of its so-called allied species as if every individual of the 

 latter had ceased to exist; the same might also be affirmed even of the individuals of 

 each species, except, 



1st, in the relations of the sexes of each species, and the result of their union ; 

 2nd, in the relation between an individual or species and the animal or vegetable 



upon which it subsists ; and 

 3rd, in cases of perfect socialism, where many individuals assist in the economy of 



the society. 



This independence in economy was the result of similar independence or isolation 

 in structural relations, and implied the genetic distinction of each species. But 

 naturalists had found it convenient to assume closer or wider degrees of structural 

 affinity as the basis of their classification, derived from the most distinctive character 

 of their various groups, of whatever rank. Thus the Mammalia appropriated to the 

 land, the birds to the air, and the fishes to the water, were characterized at once by 

 the organs which were of the greatest use in enabling them to subsist iu their respective 

 elements, and hence a primary importance was attached to the organs of locomotioD, 

 and thus groups were formed and characterized, which have been termed classes, 

 orders, families, tribes, genera, &c. It was, however, only upon the greater or less 

 degree of resemblance, either of the entire animals or portions of their organs, with 

 those which were associated with them in such groups, that these arrangements were 

 based. Various kinds of resemblance were, however, accepted by naturalists as 

 affording grounds for classification, and while some of these were highly natural, 

 others were very artificial in their nature. Species which agreed together in their 

 most essential characters were regarded as related together by affinity, but others, 

 although bearing a general resemblance, might differ widely in their important 

 organisms: this latter relationship, overlooked by the earlier naturalists, or confounded 

 by them with relations of affinity* was first clearly pointed out by Mr. W. S. 

 MacLeay, and in fact formed one of the principal key-stones of his system. Instances 

 of this kind of resemblance were then pointed out: 



1. Between members of the different kingdoms of nature : Ex. Byrrhus and a bit 

 of earth ; the larva of Geometra and a twig; Orchides and insects. 



* As where Ascalaphus, with its long-kuobbed antenna, was described as a 

 Papilio. 



