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In cases of this sort it is greatly to be regretted that the error was not 

 corrected earlier as the names have been in use for nearly fifty years, and 

 the change must occasion considerable temporary confusion. There is 

 almost no dissenting opinion, however, on the desirability of such changes. 



The matter of deciding upon the correct specific name is, however, ex- 

 ceedingly simple as compared with the determination of the proper. generic 

 name. The selection of generic names which shall stand every scrutiny is 

 respectfully offered to the logicians of to-day as a worthy substitute for a 

 discussion of the famous syllogism proving motion impossible, or perhaps it' 

 would prove as effective in promoting learned argument as the discussion of 

 how many angels can stand on the point of a needle. 



Frequent cause of change in generic names is the fact that the same 

 generic name has been used for entirely different genera, often in different 

 subkingdoms. For instance, the moss genus Thamiiium had to be changed 

 to PorotricJium because Thamnhtm was used for a genus of lichens and 

 also for a genus of flowering plants before Bruch and Schimper used it for 

 the mosses. Porotrichiim is chosen because it is the second oldest generic 

 name applied to any member of the genus. The genus Homalotheciujn and 

 the subgenus Lim7iobiinn will have to be replaced for the same reason. The 

 name P leuropus, which Mr. Dixon uses in his Handbook, is as untenable as 

 Horn a lot he cm in . 



Sometimes, however, this apparently reasonable ruling appears to be 

 more honored in the breach than in the observance. The proposed change 

 of Neckera to EUutera furnishes an excellent illustration of such a case. 

 Neckera (then written Neckeria) was first applied to the genus of mosses by 

 Hedwig in 1782, one hundred and twenty years ago. Recently it has been 

 discovered that in 1777, five years earlier, Scopoli applied the name Neckeria 

 to the flowering plant which has long been known as Corydalis. Now, if it 

 were possible or desirable to use this name for Corydalis a change would be 

 necessary, but as Neckeria is antedated for this purpose by fourteen years 

 by Capnoides, and Corydalis has been in common use for almost one hun- 

 dred years it seems extremely unlikely that Neckeria will ever cause confu- 

 sion. This position may be illogical but scientific names are supposedly, at 

 least, made for men, not men for scientific nomenclature. 



One of the most fruitful causes of changes of names as well as the most 

 legitimate is the splitting up of old genera as knowledge advances. 



Thus, the genus Hypmcm of Linnaeus included pretty nearly all the 

 Pleurocarpous mosses, Anomodon, Leskea, Thuidium, Neckera, HomaliUy 

 Leucodon, and many others. As the knowledge of mosses increased it be- 

 came necessary to separate or split off genus after genus from the original 

 Hypnum of Linnaeus. Each writer splits off what seems to him good 

 leaving the residue as Hypnum, often without a thought of what the earlier 

 author considered as typical members of his genus. This method of resi- 

 dues sometimes produces queer results. Take the case of the moss gener- 

 ally known as Dicranodoniium longirostre described under the name 

 Didymodo7t denudatus in Braithwaite's British Moss-flora. Didymodon was 



