THE NOMENCLATURE OF ARENARIA ULIGINOSA. 191 



only plant of that name cited by the Index Kewensis is the common 

 and wholly distinct American species of Michaux's Fl. Bor. Am. 1, 

 274, while the other two references to the plant under discussion 

 maintain for it the name Arenaria lapponica Spreng. (1825), which 

 is much antedated both in Arenaria, Alsine, and Spergula, and is 

 accordingly supported by no code oi- usage whatever. As further 

 incidents in this confusion may be mentioned the neglect of 

 Lamarck & De Candolle's early publication of Arenaria uliginosa, 

 and the omission of Watson's Arenaria stricta, which, as its 

 synonymy clearly shows, was employed in a sense wholly different 

 from A. stricta of Michaux. 



In 1890 (Mem. Torr. Club, ii. 37) Dr. N. L. Britton exactly 

 expresses the position of the present writer, by his footnote, which 

 runs as follows : — 



''Arenaria stricta, S. Wats., Bibliog. Index, Polypet. 98 (1878), 

 is based on Spenjula stricta, Sw. Act. Holm, xx. 229 (1799), which 

 is Alsine stricta', Wahl. Fl. Lapp. 127 (1812), and the oldest 

 name available for it appears to be Arenaria uliginosa Sclileich. 

 Dr. Watson's binomial of 1878 can in no way displace Michaux' of 

 1803." 



This position, stated so positively by Dr. Britton in 1890, is of 

 course quite contrary to the unwise Madison rule of 1893, which 

 asserts the immutability of an older specific name even when the 

 species is transferred to a genus already containing an identical 

 specific name of later date. As the writer has elsewhere shown, 

 this provision, together with the dictum of " once a synonym always 

 a synonym," would give a power to any thoughtless worker of dis- 

 placing for ever many valid specific names. Such a rule can 

 certainly never attain general acceptance, and it is a pleasure 

 to see from Dr. Britton's note of 1890 how clearly he sees its 

 disadvantages. Nevertheless it is a matter of surprise to note that 

 he did not feel impelled to follow the Madison rules in the Illustrated 

 Flora, or even in the List of Pteridophyta, &c. (which was expressly 

 prepared to illustrate the nomenclatorial system of the American 

 Association), for in both works Arenaria stricta Michx. is still kept 

 up, although the Madison rule would clearly establish Arenaria 

 stricta (Sw.) Wats, for the European plant, and force the adoption 

 of A. Michauxii Fenzl for the American. Dr. Britton's usage can 

 scarcely be due to oversight, for he had so recently shown a com- 

 plete understanding of the existence and distinctness of the two 

 species concerned. But if, on the other hand, it is to be taken as a 

 very sensible exception to an undesirable rule, it may be asked : 

 What is to become of a rigid system, if even very sensible exceptions 

 are permitted ? 



