86 SECTIONAL ADDRESSES. 



Only in one species, the long-known and often-studied Teredo navalis ot 

 Linnaeus, have we any detailed information as to variability and the 

 changes that take place during growth. In these circumstances the 

 publication of new specific names, except after prolonged study of ample 

 material, cannot be regarded as a serious contribution to knowledge. 

 Dr. Bartsch, of Washington, in his ' Monograph of the American Ship- 

 worms ' (1922) simplified his task by the assumption that any species found 

 on the coasts of the American continent must, of necessity, be different 

 from any found elsewhere, and he was thus able to write ' n.sp.' after 

 twenty-two out of twenty-nine specific names. It was soon shown, 

 however, by other American zoologists, that this assumption was without 

 foundation, and that the most destructive species on both the Atlantic and 

 Pacific coasts of North America was the European Teredo navalis. 



A thorough re\'ision of the taxonomy of the shipworms would be a task 

 of much difficulty, but it would be of great scientific interest and it might 

 even be of great practical importance. Those who are carrying out 

 experiments on the protection of timber, in this country at least, seldom 

 trouble to enquire what species they are dealing with or even whether they 

 are always dealing with the same one. Professor Barger, for instance, who 

 speaks of Teredo as a ' species ' does not seem to think that it matters. 

 Perhaps it does not, but it is just possible that it does. We do know 

 that different species differ greatly in susceptibility to changes in the 

 salinity of the water, and it seems worth while to ask whether they all 

 react in exactly the same way to the poisons that the chemists try to admini- 

 ster to them. The fact that our knowledge of their specific differences is 

 still very incomplete is no reason why the chemists should not avail 

 themselves of such knowledge as we have. 



One cause that has encumbered systematic literature with uncounted 

 pages of useless writing is the prevalent delusion that it is possible to give 

 what is called a ' complete description ' of a species. This phrase is 

 apparently intended to denote an enumeration of the visible features of the 

 organism so exhaustive as to include not only the characters differentiating 

 it from the other species already known but also those that will serve to 

 distinguish it from species yet to be discovered. Now a moment's reflection 

 will show that a lifetime would not suffice for the ' complete description ' of 

 any animal whatsoever, and, on the other hand, a very little experience 

 will convince one that it is impossible to predict the kind of characters that 

 will distinguish the next new species. Some years ago I found that all the 

 specimens of the genus Squilla in the Museum collection from West Africa 

 differed in half a dozen constant, and, once they were pointed out, 

 conspicuous characters from their nearest congeners. It happened that 

 shortly before a German zoologist had given what was intended to be a 

 ' complete description ' of a Squilla from the same region. His account 

 extended to two large quarto pages, and yet it succeeded in avoiding 

 mention of every one of the features that proved to be distinctive of the 

 species. 



If every one who describes a new species were to restrict himself to a 

 bare enumeration of the characters in which it differs from all the known 

 species of its genus, systematic papers might be vastly diminished in bulk, 

 although one suspects that the labour necessary to write them might be 



