( xlviii ) 



and no doubt is, enormous, the student, if possessed of sufficient 

 acumen to avail himself of them, has so many aids in the way 

 of what may pardonably be termed "keys" and "cribs," 

 that any alarm on that score speedily dissipates on closer 

 acquaintance. 



But systematic work, if carried out too exclusively, can 

 scarcely fail to have a narrowing influence, the one thing to 

 be avoided of all others ; and I earnestly recommend to debutants 

 that while they seek to show their power of work by attacking 

 some special subject, they should not lose sight of the 

 surroundings. 



All Systematic (including descriptive) work should aim at 

 BEING educational ; if it be not so I fail to see the necessity for it. 

 And it should be so far educational as to be intelligible, in the 

 majority of instances, to those who have not the identical mate- 

 rials before them ; otherwise what can be the use of descriptions 

 and figures ? We might just as well, in museums and private 

 collections, announce that we have a certain number of new 

 genera or species, publish their names, label the specimens, and 

 then invite workers in all parts of the world to come and see 

 them if they wish to identify their own materials with them. 



This latter remark brings me dangerously near the subject 

 of " types." When writing, in 1880, the Preface to my work on 

 European Trichoptera, the remark occurs that " the end and 

 aim of every descriptive work in Zoology should be that of 

 rendering references to types unnecessary in the majority of 

 instances," that is "educational." But I am not of those 

 who think it possible always to avoid the necessity or ad- 

 visability of examination of types. To render it absolutely 

 possible would, so it appears to me, render necessary not only 

 a thorough knowledge of what is known to exist, but also a 

 prevision of what does exist but is unknown ; the former is 

 possible, the latter more than verges on the impossible. Still I 

 fear that a considerable proportion of descriptive work is of a 

 nature that must necessitate an examination of types for its 

 elucidation, and in many cases where more care could have 

 produced other results. In such cases the descriptions had 

 better not have been written. It is to be feared that so-called 

 descriptions are often written for the sake of creating " types," 

 and in some cases with the idea of thereby instituting a money 



