342 NOTES OF A NATURALIST. 



plants the family . of Melastoinacece was decidedly 

 predominant, and within a small area I collected 

 fifteen species, eight of which belonged to the beautiful 

 genus Pleroma, One of these (P. arboreiim of 

 Gardner) is a tree growing to a height of forty feet ; 

 but the species of this family are more commonly 

 shrubs not exceeding ten or twelve feet in height. 



I was unfortunately not acquainted at that time 

 with the observations made near Tijuca by Professor 

 , j \ Arle-Ksnder Agassiz, which appear to him to give 

 evidence of glacial action in this part of Brazil. It 

 would be rash, especially for one who has not been 

 able to examine the deposits referred to, to controvert 

 conclusions resting on such high authority ; but I 

 may remark that the evidence is confessedly very 

 imperfect, and that the characteristic striations, either 

 on the live rock or on the transported blocks, which 

 are commonly seen in the theatre of glacial action, 

 have not been observed. I lean to the opinion that 

 the deposits seen near Tijuca are of the same charac- 

 ter as those described by M. Liais* as frequent in 

 Brazil. The crystalline rocks are of very unequal 

 hardness, and while some portions are rapidly dis- 

 integrated, the harder parts resist. The disintegrated 

 matter is washed away, and the result is to leave a 

 pile of blocks of unequal dimensions lying in a 

 confused mass. 



On the following day, my last in Brazil, one of my 

 new acquaintances was kind enough to guide me on 

 a short excursion in the forest, which enabled me to 



* See his valuable work, " Climats, Geolot^ie, Faune et Geographic 

 Botanique du Brcsil." 



