84 SECTIONAL ADDRESSES. 



species of animals. If we ask how many are known to-day the diversity 

 of answers we get is some indication of the confusion that exists. Some 

 years ago, at the request of the late Sir Arthur Shipley, I endeavoured to 

 get from my colleagues at the Museum estimates of the numbers of species 

 in the various groups with which they were specially conversant. Some 

 of the answers obtained were very interesting. With regard to Mammals 

 I was told ' anything from 3,000 to 20,000 according to the view you take 

 as to what constitutes a species '. For the most part, however, the 

 authorities consulted were unwilling to suggest even an approximate 

 figure for a very different reason. They told me that great sections of the 

 groups with which they were concerned were so imperfectly surveyed that 

 it was quite impossible even to guess how many of the supposed species 

 that had been described Vould survive reconsideration. 



It may be worth while to consider for a little the second of the two 

 obstacles thus indicated as standing in the way of obtaining a census of the 

 known species of animals. In the days of Linnaeus it is likely that a very 

 experienced zoologist might have been able to recognise at sight any one 

 of the four thousand species of animals that were then known, and when the 

 expansion of knowledge had made such a feat no longer possible, the 

 specialist who confined his studies to one section of the animal kingdom 

 could still aspire to a like familiarity with the species of his chosen group. 

 With this kind of knowledge it is literally true that, as has been said, a 

 systematist recognises a new species by instinct and then proceeds to search 

 for the characters that distinguish it. Some of the great zoologists 

 who were still working in the British Museum when I entered it more than 

 a quarter of a century ago, men like Albert Giinther, Bowdler Sharpe, 

 C. 0. Waterhouse and Edgar Smith, had actually an amazing personal 

 familiarity with vast sections of the animal kingdom. They had studied 

 and digested all that had been written on their subject, and, if they did 

 not carry the whole of this knowledge in their memory, they could, wfthout 

 searching, put their hand at once on the volume that would help them. 

 They had no need of ' Keys ' to help them to run down their species, 

 indeed they rather distrusted such aids for they knew how easily they betray 

 the heedless. Specialists of this type there must always be, and we may be 

 thankful for it. Nothing can altogether replace that instinctive perception 

 of affinity that comes from lifelong study. It has often happened that 

 men such as those I have named were able, when confronted with new and 

 aberrant types of animals, to allot them at once to a place in classification 

 which subsequent research served only to confirm. As time goes on, 

 however, the extent of ground that can be covered in this fashion by the 

 most industrious worker is rapidly diminishing. The torrent of publications 

 catalogued in the Zoological Record increases year by year, and the 

 specialist, if he is not to be overwhelmed by it, must not allow his curiosity 

 to stray beyond the limits of a narrow corner of the field. 



By far the greater part of this literature is written by specialists for 

 specialists, and much of it is unintelligible to anyone else. From the time 

 of Linnaeus, however, there have not been wanting publications that have 

 a different aim. We have monographs, synopses, revisions, of all sorts and 

 sizes, attempting to render possible the identification of species without 

 demanding a lifetime of study for each special group. The ideal for such 



