vill Gr: WA Aeron 
become operative in one direction, that there is a pressing 
necessity, as we urge, for a re-settlement of the priority rule in 
the interests of our science at large. 
The Principle which regulates Nomenclature is Convenience ; 
and Convenience requires that Accord shall be upheld. 
Having glanced at the historical side of the question let me 
proceed to the next points. We invite those interested to con- 
sider with us the principle in dispute, and to join us in inves- 
tigating one question of fact. 
In recent years entomologists have set themselves to work 
to discover the earliest name for every species, for this has been 
the practice, as we have seen, of writers from 1861 to 1871. In 
the words of one * authority “a generation arose who knew 
nothing of, or overlooked the circumstances connected with its 
original proposal, and who took the letter of the rule as their 
guide. And gradually there has sprung up a class of authors 
who have devoted themselves with enthusiasm to exploring 
ancient works and forgotten publications of all sorts in the 
hunt for the earliest recorded name to every species by which 
to replace the name or names in use.” As another f writer 
remarks, “‘ A little band of so-called reformers discovered the 
law and talked it over and gave it another meaning. They 
said, ‘This shows us that we ought to investigate every name 
and see if we cannot find another and older name.’ ‘They went 
at it tooth and nail, and changed every name that could be 
changed for another name.” 
What I may term the general argument put forward on the 
undesirability of this practice has not, I submit, been met with 
a satisfactory answer. I refer to that embodied in the axiom 
Communis error facit jus. Although the literature of this 
controversy has now grown to a considerable bulk, I conceive 
that the argument founded upon convenience and expediency 
remains as strong as (if it has not grown stronger than) it was 
when first put forward. Rather early in its history, the maxim 
had. to encounter the opposition of those who misconstrued 
communis; more recently it has had to meet a criticism 
founded upon a fancy rendering of jus. It may therefore be 
worth while to expound the meaning which I give to this 
apparently troublesome aphorism. As to what it does noé 
mean, “communis error” signifies “a mistake which is uni- 
versal,” and not ‘‘a vulgar error.” Jus simply means “ legal 
right,” and that is all about it. The English of the maxim 
therefore is that ‘ An error which is universal makes the legal 
right.” I apply the maxim to the solemn question of nomen- 
* Mr. Edwards; Canadian Ent. vol. v. p. 22. 
+ Mr. Newman; Zoologist, 2nd ser. 2877. 
