260 Essay, Gc. 
This Tufa is exposed in extensive stratified 
masses at the banks of the rivers and rivulets, 
which are filled with the separated fragments, 
mostly rounded by attrition: its texture is very 
loose, and the component parts, of minute frag- 
ments of basaltes, pumice, gravel and sand are 
distributed over the whole territory, and have 
probably given rise to the name of Passir, sig- 
nifying sand or gravel, for the whole district. 
The proportion of clayey parts which were 
mixed with the Tufa have also accumulated in 
extensive masses, and contribute probably to the 
productiveness on account of which the soil of 
these districts, in many places, is celebrated. 
Besides the rivulets near the villages of Ba- 
gor, Suko-rojo, Purwo kerto and Probolingo 
where it is very abundant, I noticed this Tufa, 
inastate of agglutination, in various other situa- 
tions ; it generally crumbles away on being ta- 
ken up, but has also remained entire, covering 
large surfaces which resemble the more com- 
pact Pudding-stones of Karang-bollong, and re- 
sist the effect of the water flowing over them: 
but on the application of any force, as the 
stroke ofa hammer, they instantly fall to pieces. 
The peculiarities in regard to other tufas 
this Island, will be pointed out in the explana- 
tory Catalogue. à 
In proceeding to the westward, the vicinity of 
a volcano in strongly indicated by the substances 
which have been carried down by the currents, in 
the rivers; the streams of Banjaran and Lo- 
and their basins in the dry season are filled 
* with fragments of lava, indicating apparently 4 
—* Exp. Cag, No. 30, 
