My dear Darwin

I send you a copy of the Rules of Zoological Nomenclature,² and as I insert all my letters & papers on this subject in a bound volume, I have kept a copy of this letter as a memorandum³ In your letter & accompanying paper you urge two objections against the principles involved in these rules. 1. that the law of priority, strictly enforced, as in the case of Cineras Otion &c, w^d cause much inconvenience; and 2 that the practice of attaching the name of the first describer, in perpetuity to the species, is a premium on careless description I quite admit that there is much force in both objections.

^I I do not however think that the temporary, even though great, inconvenience attending the enforcement of a right principle, ought to prevent us making a change which will be beneficial in the end. When a species or a genus has a plurality of names, there are three principles which may guide us in selecting one of these names for permanent & exclusive use. We may choose the oldest name, or the one which is best in point of meaning, or the one which has been most generally adopted by others. Now it seems plain that naturalists, one and all, ought to decide which of these 3 principles to follow in future, and to adhere to that principle, to the entire exclusion of the two others. Leave it open to them to follow sometimes one rule and sometimes another, and you may as well have no rule at all. Which of the three principles then are we to select?

1. The rule of invariably selecting the oldest name has the advantage of being wholly based on fact and not on opinion. It is an eternal immutable fact that AB did in a certain year, describe for the first time a certain species, and give it the name CD. All the naturalists of all ages and countries who may have occasion to investigate the (human not the natural ) history of a species, must ultimate arrive at this one terminus, viz. the date of its first baptism. For instance, G. R. Gray in his Genera of Birds,⁴ has rigidly followed this rule, and I, who for the last 10 years have been working out the synonymy of birds independently of Gray, have also followed it.. On comparing his results with mine, I find that we almost invariably agree in the specific name which we adopt; where we differ, it is a certain proof of error or of incomplete research, on one side or the other, and I immediately set to work to find where the error lies. The true (according to the above principle) name of a species is thus worked out with as much certainty as a mathematical equation.

On the other hand the objection to this principle is that the oldest names are frequently neither the best in point of meaning nor the most widely used by other writers. In the former case however the evil seems to me to be trivial, in the latter, transient, as will be shown under the remaining heads.

2. The principle of selecting a name solely because it is the best in point of meaning, is hardly worth discussion as no one I believe, would now defend it. A name is not a definition, and it may have no meaning or etymology at all, and still accurately indicate its object. The goodness of a name is entirely a matter of opinion and taste. One man has a fancy for geographical names, another (like Swainson)⁵ repudiates them & substitutes others of his own invention, with the delightful ‘mihi’ attached. Were this permitted, the multiplication of names would be wanton and perpetual, and I conclude therefore that such a principle will never be sanctioned.

3. The principle (to which you refer) of selecting in preference those names which have already been so selected by the greatest number or the most authoritative writers (irrespective of priority) is more plausible than the last. There is no doubt great inconvenience caused by substituting a name just dug up out of some obscure provincial periodical, merely because it is a year or two older than the one which has long been circulated in the writings of Cuvier, Lamarck, and their disciples. Still I can only look upon this as an inconvenience to which the present generation are bound to submit for the sake of posterity and the ultimate benefit of science. Admit the principle that the oldest names are to give way to those in most general circulation, and you leave the terra firma of fact for an ocean of conflicting opinions. Who is to decide what names are the most widely circulated, or what writers are the highest authorities? For many years Montagu’s⁶ names of Mollusca were most generally used, & his authority considered highest, in England, while Lamarck’s & Draparnaud’s obtained currency in France, and zoology would soon be in a pretty mess if its nomenclature became a matter of national feeling. But once get English & French zoologists to subscribe to the law of priority rigidly enforced, and as soon as the first inconvenience of the change was got over, they would enjoy the immense convenience of an absolute identity in their scientific nomenclature.

And I further assert that Cuvier, Lamark, & every one else who has used the names Coronula, Cineras and Otion (for instance) has been guilty of a great (though unintentional) injustice to the German who gave prior names to those genera. He may (and for ought I know did) have given much labour and original research to the investigating of those genera, he may even have given a better monograph of them than anyone since, yet he had the misfortune to be a poor doctor in some village of Pomerania, and was only able to publish his memoir in the “Stralsundishes Magazin”, of which perhaps only 100 copies were ever printed. All this is to be regretted, still I say that the compilers of monographs or of systematic works are bound in justice to search out the cognate labours of others in ever possible direction, and where they have (even unavoidably) overlooked other persons’ writings, they must still pay the penalty by having their nomenclature superseded in favour of a prior one. Scientific natural history has now become as much a matter of literary research as of physical observation. I have had this forcibly brought home to me last autumn, when looking through the fine collection of foreign periodicals in the Bodleian Library, when I was astonished at the mass of original memoirs on zoology and other sciences which seem never to have made their way beyond the scientific but limited coterie in whose periodical they are printed.⁷ Authors should be encouraged to publish matters of science in standard and accessible periodicals (& the Association code has a clause ([SYMBOL]D) to that effect, still we cannot prevent them from doing otherwise, and we must (as the law does with libels) regard the act of printing as tantamount to publication, and deal out equal justice accordingly.

4. There is a fourth principle which I had overlooked and which might be proposed as a rule for selecting one name out of a plurality of synonymes, viz to adopt the name of the person who has given the best definition or description of the group or species. You seem favourably inclined to this principle, and if it were practicable it would certainly be useful as a premium upon good work. But I fear it would be impracticable, first because (like principles 2 & 3 supra) it is based on opinion & not on fact, and secondly because a man may give the best definition or monograph possible of a species or group in the then state of science, but another man 20 years later may be enabled by the advance of knowledge & the arts to publish a far better description & to give a new name on the strength of it. There would then be a perpetual and unseemly scramble for the supposed honours of coining new names.

Upon the whole then I cannot give up the grand principle of priority, a principle simple and easy in its application, because based on historic fact, useful as reminding us of the date of first discoveries & the subsequent progress of science, and just in its application to all men. It doubtless causes frequent inconvenience in particular cases, but this inconvenience is transient, and will cease as soon as the earliest name of each species or group has been successfully [ illuminated] and has passed into general, and above all perpetual currency, for no further change will then be possible to those who obey the law of priority.

Of course the law of priority is only applicable where the original definition (however brief or incomplete) is yet sufficient to remove all moral doubt of the identity of the species. Where you cannot prove identity, you cannot assert the name to be really a synonyme, and in such cases it should be simply added to the caput mortuum of nominal species which should form an appendix to every good monograph—

II. I have next to notice your second objection—that retaining the name of the first describer in perpetuum along with that of the species, is a premium on hasty & careless work. This is quite a different question from that of the law of priority itself, and it never occurred to me before, though it seems highly probable, that the general recognition of that law may produce such a result. We must try to counteract this evil in some other way

The object of appending the name of a man to the name of a species is not to gratify the vanity of the man, but to indicate more precisely the species. Sometimes two men will by accident give the same name (independently) to two species of the same genus. More frequently a later author will misapply the specific name of an older one. Thus the Helix putris of Montague is not H. putris of Linnæus, though Montague supposed it to be so— In such a case we cannot define the species by Helix putris alone, but must append the name of the author whom we quote. But where a species has never borne but one name, (as Corvus frugilegus) and no other species of Corvus has borne the same name, it is of course unnecessary to add the author’s name. Yet even here I like the form Corvus frugilegus Linn., as it reminds us that this is one of the old species, long known, and to be found in the Systema Naturæ &c.

I fear therefore that (at least until our nomenclature is more definitely settled, it will be impossible to indicate species with scientific accuracy, without adding the name of their first author. You may indeed do it as you propose, by saying in Lam. An. Invert. ⁸ &c, but then this would be incompatible with the law of priority, for where Lamark has violated that law, we cannot adopt his name

It is nevertheless highly conducive to accurate indication to append to the (oldest) specific name, one good reference to a standard work, especially to a figure, with an accompanying synonyme if necessary. This method may be cumbrous, but cumbrousness is a far less evil than uncertainty.

It moreover seems hardly possible to carry out the priority principle without the historical aid afforded by appending the author’s name to the specific one. If I, a priority man, call a species C.D., it implies that C.D is the oldest name that I know of, but in order that you and others may judge of the propriety of that name, you must ascertain when, and by whom, the name was first coined. Now if to the specific name C.D, I append the name, A.B, of its first describer, I at once furnish you with the clue to the date when, and the book in which, this description was given, and I thus assist you in determining whether C.D be really the oldest, and therefore the correct, designation.

I do however admit that the priority principle (excellent as it is) has a tendency, when the authors name is added, to encourage vanity and slovenly work. I think however that much might be done to discourage those obscure and unsatisfactory definitions of which you so justly complain, by writing down the practice. Let the better disposed naturalists combine to make a formal protest against all vague, loose and inadequate definition of (supposed) new species. Let a committee (say of the Brit Association) be appointed to prepare a sort of Class List of the various modern works in which new species are described, arranged in order of merit. The lowest class would contain the worst examples of the kind, and their authors would thus be exposed to the obloquy which they deserve, and be gibbeted in terrorem for the edification of those who may come after.

I have thus candidly stated my views (I hope intelligibly) of what seems best to be done in the present transitional and dangerous state of systematic Zoology. Innumerable labourers, many of them crotchetty and half educated, are rushing into the field, and it depends I think on the present generation whether the science is to descend to posterity a chaotic mass, or possessed of some traces of law and organization. If we could only get a congress of deputies from the chief scientific bodies of Europe & America, something might be done, but as the case stands I confess I do not clearly see my way, beyond humbly endeavouring to reform Number One.

Yours &c | H. E. Strickland