219 



however from the investigations of Sidnky J. Hickson, the cliffs 

 consisting of limestone were covered by a thin bed of guano, which 

 seen from a distance looked like chalk '). 



The third and last tinding-place was traced by J. J. Pannkkoek 

 VAN Rheden in Pulu Bafii, a little island near Pnlii Seraya ketjil, 

 westward of Flores'). The guano forms there only a thin bed spread 

 ovei" the surface of a few ares, the quantity was valued at only 

 about one hundred cubic meters'). 



From the description, at all events of that of the two tirst- 

 mentioned places, it appears that the gnano was leached, i.e. a not 

 unimportant part of the [thosphoric acic had found its way to the 

 sea, by which the formation of phosphorite, as under equal circum- 

 stances in every monsoon-territory, was prevented. 



The guano-beds in limestone-grottoes originating chiefly from bats 

 will be preserved from such a fate. The quantity of these formations 

 is however usually very slight, as will appear from the following 

 summary. 



In the S. and E. department of Borneo the grottoes of Mount 

 Hapu are especially known, in these grottoes the existing guano- 

 bed attains a thickness of at least 2 m. The quantity of guano that 

 is found in the grottoes of Mount Lampinet was even valued at 

 'JÜOOO tons'). It is however far surpassed by that of the grottoes 

 of Gomanton on the river Kinabatangan in British North Borneo 

 where it is said that the thickness of tlie guano-beds amounts to 

 50 feet^). 



The bottom of the numerous liinestijne-grottoes in Sarawak is 

 likewise usually covered with a bed of bat- and liird-guano some- 

 times mixed with river-mud. It is however of no significance ^). 



') Omzwervingen in Noord Celcfjes. Tijdsclir. Ned. Aard. Genootsch. (2) 4. M. 

 U. A. f887, p. f35. - A Naturalist in Celebes. London 1889, p. 33. 



2) Ovcrziclit van de geograpliisclie en geologisclie gegevens verkregen bij du 

 Mijnbüuvvkundig-geoiogisctie verkenning van liet Eiland Flores in 1910 en 1911. 

 Jaarboek van het Mijnwezen 40, 1911. 13atavia 1913, p. 2;2tj. 



■*) F. J. Maier, Sclieikundig onderzoek van Vogelmesl, afkomstig uit de grotten 

 van den Goenoeng Hapoe in de afdeeling Riara Kanan en Kiwa (Zuid- en Ooster- 

 alUeeling vau Borneo). Natuurk. Tijdschr. Ned. Ind. 29, Batavia 1867, p. 114—129. 



+) Die Vogelnestgrotten von Gomanton auf Nord Borneo. Globus 46. 1884, 

 p. 31, according to tlie North Borneo Herald of 1st March 1884. — H. Pryer. An 

 Account of a Visit to the Bird's nest Caves of Britisli North Borneo. Proceed. 

 Zoolog. Soc. London 1884, p. 532 — 538. — D. D. Daly, On the Caves containing 

 Edible bird's nests in Britisch North Borneo, ibid. 1888, p. 108—116. 



») A. Hart Everett. Report on the Exploration of tlie Caves of Borneo. Proc. 

 Roy. Soc. 30. Loudon 1880, biz. 310—313. — Th. Posewitz. Höhlenforscliungen 

 in Borneo. Das Ausland 61. Stuttgart Miinchen 1880, pp. 612 — 613. 



