Mr. J. iVPClelland on Indian CyprinidEe. 195 



from the Gonorhynchs, Me pass through a succession of spe- 

 cies connected together by direct relations, and after arriving 

 at an opposite point {Opsarius), at which the forms, habits, 

 and structure differ totally from those with which we set out, 

 we are led back again through a succession of different forms 

 from those through which we passed at first, to the point 

 from which we started. 



It has resulted from jMr. MacLeay's views applied to the 

 analyses of the classes of birds, quadrupeds, and insects, that 

 " the contents of such a circular gi'oup are symbolically (or 

 analogically) represented by the contents of all other circles 

 in the animal kingdom ;" but as such analyses have not yet 

 been carried through fishes and reptiles, the conclusion just 

 quoted has been submitted rather as a proposition by the 

 distinguished author of the ' Geography and Classification of 

 Animals,' whose next proposition is, " That the primary divi- 

 sions of every group are characterized by definite peculiarities 

 of form, structure and oeconomy ; which, under diversified 

 modifications, are unifoiTn throughout the animal kingdom, 

 and are therefore to be regarded as ih.e primary types of nature." 

 1 shall now merely copy from the work referred to one of the 

 tabular views of the parallel relations of well-known groups of 

 Mammalia and birds, adding in the first column what appears, 



naeau Transactions,' vol. xvi.), and the whole of these observations have 

 since been confirmed and their results more fully made out by Mr. Swain- 

 son, who also has extended his views to the Mammalia. About the same 

 period with the publication of the ' Flora? Entomologicae,' the progression of 

 affinities began to acquire additional interest among botanists. M. Agardh 

 and M. DeCandolle both published their views on the subject, the first in his 

 ' Botanical Aphorisms,' and the second in the 'Memoires du Museum ;' when, 

 without knowing what had been done by Mr. MacLeay, Mr. Fries an- 

 nounced the same results in the Fungi, attained by a different form of 

 analysis. Similar views have since been more extensively applied to plants 

 by Professor Lindley, in the last edition of his ' Introduction to the Natural 

 System.' 



Writers on natural history in the present day may be divided into three 

 classes ; first, those who recognise no rules but such as appear to be laws of 

 nature, and taking nature as their guide, form their views according to the re- 

 sult of observations which are Tiot confined to external characters, but embrace 

 all that concerns natural objects. The second class consists of naturalists 

 who pursue the easier course of following authorities, but their works con- 

 sist chiefly of technicalities derived from external chai'acters indiscriminately 

 applied to genera and species ; their higher groups are consequently con- 

 structed according to rule rather than nature. The third class comprises 

 describers of species, whose books are only remarkable for their size and 

 expense. Nor can I altogether overlook upon this occasion another class of 

 persons, who, though they are not naturalists, and scarcely even allow us 

 to call them writers, yet exercise but too often an influence in societies de- 

 trimental to the objects of such institutions and the real advancement of 

 science. 



O 2 



