R. D. Verbeek — Geology of Sumatra. 481 



Zurich ; showed that the four series or groups 5a, 5b, 5c, and 5d, 

 belong to the Tertiary, and probably all to the Eocene period. 



Among the Fishes from 5a Prof. Geinitz determined Fistularia 

 Koenigi, Agass., which occurs in the Eocene schists of Glarus (Swit- 

 zerland) ; some other Fishes strongly resemble Osmeroides (subgen. 

 Sardinoides, v. d. March) raicrocephalus, Miinst., and Osm. (Sard.) 

 Monasterii, from the " Plattenkalke " of Sendenhorst, Westphalia, 

 which are of Senonian age (described and figured by v. d. Marck in 

 " Palasontographica," vol. xi. pi. 6, and Agassiz, " Poissons fossiles," 

 vol. v. pi. 60c2). 



The fossil Plants from 5a have a more Miocene than Eocene cha- 

 racter. Some have already been described and figured by Prof. 0. 

 Heer in the " Abhandlungen der schweizerischen palaontologischen 

 Gesellschaft," vol. i. 1874. According to Prof. Geinitz, there are 

 some Echinids from 5d nearly related to Prenaster Alpinns, Desor 

 (Desor, " Synopsis des Echinides fossiles;" 1858, p. 401, and W. A. 

 Ooster, " Petrifications- remarquables des Alpes Suisses ; les Echino- 

 dermes,"p. 112), and to Periaster subglobosus, Desor (op. cit. p. 385) 

 and W. A. Ooster (op. cit. p. 109), both from Eocene or Nummu- 

 litic rocks of Switzerland. It is therefore highly probable that 5d 

 belongs to the Eocene period. As 5d is the upper part of all these sedi- 

 mentary deposits, the formations 5c, 56, 5a, must be of Eocene age 

 too. It is not at all probable that 5a belongs to the Upper Cretaceous 

 (Senonian) formation, firstly, because the Senonian character of some 

 Fishes from5a is easily explained, the Marl- slates being the oldest of all 

 our Eocene deposits, and the fossils from the Senonian " Plattenkalke " 

 of Sendenhorst, although older, having a strong resemblance to those 

 from Eocene rocks of other parts of Europe ; secondly, because rocks 

 of Cretaceous age are wanting in the Highlands of Sumatra; thirdly, 

 because' the Marl-slates at the top of the series become sandy, and 

 pass into the coal-bearing sandstones of 5b, which are most probably 

 of Tertiary age ; fourthly, because the fossil Plants from 5a have a 

 Tertiary, and even more of a Miocene than Eocene, character. 



The Eocene formation of Sumatra is thus represented in four groups, 

 or etages. That of Borneo, according to my investigations-, is only re- 

 presented in three groups. The lowest of these latter contains the 

 coals ; the middle part consists of marls, with some few Nummulites 

 (Nummulina Pengaronensis, Verb.) and many specimens- of Orbitoides 

 discus, Rutim.) ; the upper part is a nummulitic limestone with 

 millions of Nummulites and some Orbitoides. 



Perhaps the coal-bearing sandstones of Borneo are the equivalent 

 of the Sumatran coal-bearing formation 5b ; the Borneo marls, the 

 equivalent of the marl-sandstones 5c ; and the nummulitic limestone 

 of Borneo may be the equivalent of the limestone with Orbitoides 5d ; 

 in which case tbe equivalent of the marl-slates with Fishes would be 

 wanting in Borneo. But as there is a very great difference between 

 the Eocene fossils from Borneo and those from Sumatra, this can only 

 be proved by a careful comparison of the fossils. Those which I 

 gathered at Borneo will soon be described by Dr. 0. Bottger, Frank- 

 fort-on-the-Maine ; Dr. von Fritzscb, Halle ; and Dr. Geyler, Frank- 



