114 NATURAL SCIENCE. 



April, 



The limestone stage (7) consists of a hard white or bluish lime- 

 stone, containing numerous fossils (Corals, Sea-urchins, Lamelli- 

 branchs, Gasteropods, Orbitoides and Nummulites). This stage 

 appears to be the equivalent of the Nummulitic Limestone of 

 Europe. 



Schwaner describes it in the following terms : " The limestones 

 possess the undoubted characteristics of a littoral formation : they 

 consist of enormous aggregates of coral and broken shells, inter- 

 mingled with the spines of echinoderms ; and resting on a bed of hard 

 rock, they follow the boundaries of the high ground, into its bay-like 

 inlets and round its projecting promontories." 



Space does not permit me to give details as to the development 

 and distribution of these important Eocene deposits, nor to describe 

 their fauna and flora.5 Suffice it to say that stage a has been found 

 to reach a thickness of 524 feet ; stage ^e, to 820 feet ; and 

 stage 7. to 295 feet. With regard to the fauna, eighteen species of 

 Gasteropods have been determined, all of which are marine types. 

 They indicate a tropical climate, the majority of the species having 

 their nearest representatives in the present fauna of the Indian 

 Archipelago. The Lamellibranchs are better represented than the 

 Gasteropods, and comprise an abundance of characteristic marine 

 forms, indicatmg both deep and shallow seas. The Nummulites 

 belong to four different species, two of which are peculiar to Borneo 

 {N . pengaronensis, Verb. ; N . sub-brongniavtl, Verb. ; N. biaritzensis, 

 d' Arch. ; N. striata, d'Orb. var.). The coral fauna of the Nummulite 

 beds consist of species peculiar to Borneo (belonging to the Turbino- 

 lidae, Stylophorinae, Astraeidae, Madreporidae, and the Poritidae) and 

 are of a reef-forming type. The flora has an Indian character, 

 showing a remarkable resemblance to types now living in the East 

 Indies.^ 



The Eocene strata have been pierced in numerous places by 

 the eruption of andesitic lavas. These lavas are bedded, and are 

 accompanied by tuffs. Since they have broken through the highest 

 beds of the limestone stage, they are probably of Miocene age. 

 Above the andesites lies a series of shales and sandstones, which 

 Verbeek describes as Late Tertiary (Miocene). The lower beds 

 consist of soft shales and harder marls. The greenish sandstones 

 which lie above them have, in great measure, derived their material 

 from the andesites and tuff. These Miocene beds contain occasional 

 seams of brown coal, which is very inferior as fuel to the black coal 

 of the Eocene beds. 



' An admirable summary, with full reference to the literature, will be found 

 in Posewitz's "Borneo." 



•5 " The vegetation of the Sunda Islands has retained its Indian character, from 

 the Eocene period down to the present time, although the Tertiary floras of Europe 

 have been considerably modified." Geyler, Jaarb. v. h. Mynwezen in Ncdcrl.-Ind. 

 1879. II. 



