Occasional Notes. 375 



less even such an index is by no means to be despised. 

 Most of his early " finds" will be included in this list — 

 in faft, unless he has special opportunities he will hardly 

 discover any species not mentioned. Having checked 

 off every plant that he has seen, the list will be much 

 reduced, so that instead of having to wade through a 

 crowd of species he only has perhaps half a dozen to 

 investigate. If he is " well up" in the genera and their 

 divisions he can often make a fair guess by elimination. 

 Thus, he knows all that are checked off, so the new 

 plant is not one of these — then it belongs to a certain 

 division of which only one or two are strangers, 

 therefore it is likely to be one of these, and there may 

 be something in the habitat that makes the enquirer 

 morally certain that it can only be so-and-so. Now, to 

 confirm this guess it is necessary to have access to a few 

 books which are perhaps not so easily procurable. First 

 among these we place the " Contributions towards a 

 Flora of South America'^ published in Hooker's Journal 

 of Botany. This is very incomplete as a list of Guiana 

 plants, yet there are many species first described here. 

 Then come three books which will be found very useful 

 as they are authorities for many species, viz. Aublet's 

 '* Flora de la Guyane Fran^aise," Meyer's " Primitiae 

 Florae Essequeboensis,"and Rudge's " Plantarum Guianae 

 Icones." Finally, we have the whole field of botanical 

 literature, commencing with that indispensable book 

 Decandolle's " Prodromus." An exceedingly useful 

 work is the " Flora Braziliensis" which has been coming 

 out in parts for over half a century, but unfortunately it 

 is beyond the means of most botanists. 



We have presumed that the student has obtained 

 ; H 2 



