20 REMARKS ON THE PRINCIPLES OF 



subject of classification being, at present, very unsettled ; so that the 

 greatest names of thoughtful observers of nature, and useful labourers 

 in bringing to light new facts, may be quoted in support of the most 

 opposite methods, and teachers in different schools are exceedingly 

 likely to vary in their plans, if my esteemed friend Dr. Dawson's 

 views had differed very widely from my own, I should neither have 

 been greatly surprised, nor have thought myself at all called upon to 

 enter into controversy with him on the subject. But when I find in 

 his paper a remarkable agreement on what are, [certainly, the most 

 important points, with the principles I have maintained and taught 

 for a good many years, and where he differs from me in matters of 

 detail, which are still of great interest, that he has given his reasons 

 concisely and clearly, so as to afford the opportunity for a candid, 

 discussion of the merits of the case, I am tempted, at once, to express 

 my sense of the great value of much of what he has done, and to ask 

 the attention of the lovers of natural science in' our Society to the 

 reasons which prevent my agreeing with the author on certain points, 

 and seem, to me, to justify different conclusions. Any notice I may 

 take of the points, in my view the most important, in which I agree 

 in opinion with Dr. Dawson, is not intended to add to the weight of 

 his statements by my humble approbation ; but simply to make it 

 understood how far we proceed together, where many others take a 

 different course, and what the questions are which I propose to 

 discviss : questions which, though in some respects subordinate, have 

 all the interest which arises from extensive practical influence on our 

 arrangements. Dr. Dawson's remarks on species seem, to me, just, 

 and of fundamental importance, deserving the attention of all stu- 

 dents of natural history, and well fitted to counteract some prevalent 

 errors.* The section on "genera and higher groups" is, also, in 

 general accordance with my views, and seems to me a well considered 

 statement of great principles ; but I would venture on one or two 

 observations, occurring to me, in connection with it. The author 



• I must confess that I cannot help desiring a more satisfactory definition of a species, 

 than a group of individuals which may have had a common descent. I have thought Of 

 something of this kind : a gronp of beings, having similar organs for the performance of tho 

 vital functions, disposed precisely on the same plan, and— allowing for differences of age or 

 sex and minor peculiarities, shown by experience to be unimportant,— developed in the same 

 relative proportion. If, however, this definition could be made entirely unobjectionable, as 

 clearly marking all that enters into the received idea of a species, it would, of course, leave 

 questions respecting their origin and permanence exactly as they are, and we could go no 

 farther without assuming the very points which require proof, so that nothing can be 

 practically gained in this direction. 



