ORCHIDACEiE 



late unguiculatum, usque ad medium dilatatum nunc constric- 

 tum demum prope apicem leviter dilatatum, trinervium, ad basim 

 utrinque in caudam elongatam, gracilem, plus minusve 1 mm. 

 longam productum. Columna medioeris, stigma simplex, vix bi- 

 lobatum. Rostellum baud productum, breviter emarginatum. 

 Anthera late ovata, 1 mm. longa. 



Allied with S. Lucayana Cogn. The small flowers and bicau- 

 date labellum are differentiating characters. 



This species is apparently a member of the group recently- 

 described under the genus Mesadenus by Dr. Rudolf Schlechter 

 in his monograph of the Spiranthinae.^ I have not taken up this 

 name for the Trinidad species, because I am convinced that 

 Schlechter's treatment of the Spiranthinae needs to be carefully 

 tested from beginning to end before it is adopted as a basis for 

 progress. Schlechter's monograph is very subtle in conception, 

 and is based on characters which are too recondite for practical 

 purposes. It is certainly perplexing and one may fairly question 

 the advisability of accepting its innovations. 



Dr. Schlechter has, it is true, revealed some clear lines of de- 

 marcation in a group that is large and heterogeneous, yet sev- 

 eral of his new genera seem hardly isolable from Spiranthes and 

 rest on characters that are difficult to define. Whether or not the 

 lines of demarcation are sufficiently clear for generic separation, 

 it is patent, as one uses Schlechter's system, that difficulties have 

 been shifted rather than removed. 



The conception of genera admittedly rests on personal judg- 

 ments. The history of biological science indicates quite clearly 

 that personal judgments in the erection of genera receive harsh 

 treatment when they fail to elucidate relationships, when they 

 give place to burdensome perplexity and when they emphasize 



^Beihefte Bot. Centralbl. 37, Abt. 2 (1920). 



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