D.— ZOOLOGY. 87 



correspondingly increased. It may be a counsel of perfection to suggest 

 that no one should introduce a new specific name without undertaking at 

 least a partial revision of the genus including it, but there are very many 

 instances where the multiplication of species might with advantage be 

 postponed until we learn something about those that are supposed to be 

 ' known.' 



The number of described species of animals has been estimated at 

 something in the neighbourhood of three-quarters of a million. It is not 

 at all improbable that between a quarter and a third of that number would 

 be suppressed as synonyms or put aside as ' species inquirendse ' by careful 

 monographers and that in many groups the proportion would be far higher. 



The prospect is not one that can be contemplated with any satisfaction. 

 The successively expanding volumes of the ' Zoological Record ' give us a 

 picture of systematic zoology being smothered under the products of its 

 own activity. The confusion will grow steadily worse unless systematists 

 come to realise that the mere description of new species is a far less important 

 thing than the putting in order of those that are supposed to be already 

 known, and until, on the other hand, zoologists in general cease to regard 

 taxonomy as a kind of menial drudgery to be done for them by museum 

 curators. 



I have alluded to another obstacle to obtaining an enumeration of the 

 animal kingdom in the divergences of opinion as to what constitutes a 

 species. I am not sure that these divergences are not sometimes over- 

 estimated. I think that it will be found that in most Orders of animals there 

 exists a considerable body of species regarding whose limits there is no 

 serious difference of opinion among competent systematists ; but alon<Tside 

 of these we find in almost every Order, in most families, and even in rnany 

 genera, a ' difficult ' residue in wliich the delimitation of specific groups 

 sometimes seems to be little more than a matter of personal taste. My 

 colleague Mr. Robson has recently brought together a great deal of infor- 

 mation on this subject in his book ' The Species Problem,' to which I would 

 refer anyone who needs to be comanced how complex the problem really is. 

 For our present purpose it is enough to take the empirical fact that the 

 majority of animals can, with more or less trouble, be sorted into assem- 

 blages or kinds that we call species. We have seen how imperfect and 

 confused is the present state of knowledge even as regards the mere 

 description and identification of these kinds. 



The business of the systematist, however, does not end with identifi- 

 cation. Even identification requires some kind of classification, if it is only 

 the classification of the dictionary. Since the time of Linnaeus, or rather 

 since the time of John Ray, zoological systematists have believed in the 

 existence of a Natural System of -classification which it was their business 

 to discover ; since Darwin, it has seemed plain that this Natural System 

 must be, in some way, based upon Phylogeny. It is now realised that 

 the relation between the two is not always so simple and straightforward 

 as it once appeared to be. Dr. Bather, in his presidential address to the 

 Geological Society in 1927, discussed the historical and philosophical 

 bases of biological classification. He concluded that ' The whole of our 

 System, from the great Phyla to the very unit cells is riddled through and 

 through with polyphyly and convergence,' and that ' Important thou<^h 



