BY THE REV. J. E. TENISON-WOODS, F.G.S., &C. 735 



radiating lines of fissure are composed of andesite and trachyte. 

 All the recent ejections of the volcanoes have consisted of rhyolite 

 or basalt. 



As I have said there are no proper lava streams from which this 

 can be studied. The Spanish geologist considers that in the lowest 

 formation or the basal foundation of the island, there are true lava 

 streams of a basaltic chai-acter. This would mean that the earlier 

 eruptions, or rather those which built up the island after the sub- 

 sidence of the great crater, were accompanied by outflows of lava. 

 From this point of view the whole history of the present crater 

 is very diflicult to unravel, but without entering into the matter 

 it may be sufficient to say that what evidence this volcano offers, 

 though it is but slight, is in favour of Richthofen's theory. The 

 seneral character of all the emanations is basaltic and doleritic. 

 Trachyte is, however, found in a few places, as for instance the 

 island of Napayong, and about Mount Sungay in a barranco close 

 to the town of Talisay. I shall subjoin to this essay the list given 

 by Senor Centeno of the minerals which he has met with, premising 

 that I have not been able in every case to verify the references, or 

 visit the localities. I may mention also that there is a trachytic 

 rock visible at Binintiang Malaki, but no rhyolites, andesites or 

 propylites as far as I have been able to make out. 



Catalogue op the Rocks of the Volcano op Taal and of 

 THE Mountains in the vicinity op the Laguna op 



BOMBON.'^- 



1. Sulphur crystallized and in concretions. Volcano of Taal, 

 bottom of the crater on the north-east border of the yellow lake. 



2, 3, 4. Crystals of gypsum surrounded by a nucleus, probably 

 vegetable, which has disappeared and has been replaced by sulphur. 

 The specimens also contain alum. Ditto. 



5. Crystals of gypsum. Ditto. 



*In the following list *.he numbers up to 74 are from the district of the 

 town of Talisay, 75 from Lipa, 76 to 79 from Cuenca, and SO from Taal. 



