June 9, 1909 75 



is identical with the plant described by Kngelmann in the Cac- 

 teae of Emory's Reconnoissance, under the name of M.fascicu- 



lata. No type specimens of M. fasciculata are known to exist, 

 and the figure and description are inadequate, yet they leave no 

 doubt in my mind, and I feel justified in treating M. Thornberi 

 as a synonym. 



One prominent American botanist, deciding upon segregat- 

 ing four new species from what had before been recognized as 

 one, found himself unable to determine to which of his four spe- 

 cies the accepted name should be given, cut the gordian knot by 

 describing all four as new species, leaving it to future botanists 

 to determine which of his four names should be relegated to syn- 

 onymy. There is no doubt about this incident, as the man told 

 me the tale himself, but I hope the practice has not been a com- 

 mon one. 



In the study of the Cactaceae there are many instances 

 where one feels inclined to treat the bulk of the older published 

 names as nomina nuda and begin all over again. It is impos- 

 sible for us in a great many cases to determine what plant was 

 originally given a stated name — Opuntia tuna being a well 

 known instance. Mammillaria elegans, one of our best known 

 cacti in cultivation, certainly does not agree with DeCandolle's 

 description, and the difficulties of a reconciliation can be seen 

 by a comparison of the original with Schumann's more recent 

 description. I have had several distinct species given this name 

 by those who have given special study to cacti. 



I believe that many of the new species in Cactaceae pub- 

 lished in recent vears are based on plants previously described. 

 But where any doubt exists, and where no type has been pre- 

 served, it would be well for botanists to recognize as law the 

 rule that the older names should not be revived at the expense 

 of well established names. This rule would save us from the 

 re-establishment of many doubtful generic names as well as spe- 

 cific names, and preclude the use of such a name as L 'actus from 

 future generic application — a name pretty well worn out. 



San Diego, California, 



