148 Mil. J. IJALL ON THE liOTANi* 



worn down, hi<;h inoiiulaina of Brazil. To sumo botanists the 

 Melusfornncew uuiy ap|)(.»nr to present a more important exemption. 

 Looking at the very numerons mudi(ication8 whicli the earlier 

 typea of that family iiave iiiulergone, and to their wide ditViiJ^ion 

 thrc)nghont the world, wc are, in any ease, foreed to attrihutc to 

 them a very great antiipiity. Further, we find so n\any repre- 

 sentatives of the ehief Ameriean types of the Ord^r inhabiting the 

 su1)alpine zone of the Andes that, as it ap[)ears to nie, the 

 prubability of their mountain origin is at least a jujt unreasonable 

 hypothesis. An ilhist ration of the view here defended is 

 ath>rdeil by the tribe ThibitUil'ue of Vacciniacecr, whieh, exceptnig 

 two Himalayan gi^iera, are exelusively American, and mainly 

 inluibit the 8h»])es of llie Xortlu'rn Andet*. Several ropre.<entalivc^ 

 of the group, t^o distiiiet as to be ranked as separate genera, have 

 cxttMided to tlie tro[:ieal zone of equatorial America, and some of 

 these appear in the islands (»f the Cariba^an Sea. Yet lew 

 botanists, I think, would hesitate to regard the ^^ortliern Andes 

 a« the home whoneo these aberrant types have been developed. 

 It is easily eoneeivablc that in the course of their gradual 

 niigration, while exposed to many vicissitudes of external con- 

 ditions, new species, and even new generic types would have 



been developed, 



1 cannot close this sliiiht notice of the flora of Buenavcntur* 

 witliout remarking that it is a spot well deserving the aitt^ntion 

 of any naturalist visiting South America. It is easy of accc3«, 

 is said to have a fairly heallhy climate, and would atTord a w»* 

 v< nienl centre for excursions in a reifion sin'Mihirlv rich in forini 

 uf life, and which has hitherto been very imperfectly explorcd- 



Flora of Payta in Xorth Peru. 



Although there is very little to record, I think it may be 

 Useful to note the sin^eies cidleeted during a walk of about U^o 

 hours over the plateau behind the little town of Pavta in >'orth 



if 



iVru. The vegetation of the hot and dry desert regions of the 

 earth e\ery\\hcre exhibits some eonunon features. The exi>tenc© 

 of such regions is determined by the extren^e scarcity of a^ueoui 

 precipitation in the form of rain or dew. The surface l>cmi; 

 ordinarily rock, more or less covered with sand, few seed* »t^ 

 devch»p<Ml even on the rare oeea?«ion» when sufficient n>uij»turc i* 

 present; and such plants as arc sccu are scattered nt »w<^ 

 intervals. Annual species, whieJi appear after the rare occasion* 



