322 ORTMANN — DISTRIBUTION OF DECAPODS [Aprils, 



that a number of these islands possess very old, possibly Archaic 

 rocks, which are overlaid directly by Tertiary beds, thus giving 

 evidence of an intervening extended land period, during which 

 no sedimentation took place. This has been demonstrated for the 

 Philippine Islands, where an Eocene, Miocene and Pliocene series 

 follows on top of old crystalline schists. 1 Similar conditions are 

 said to prevail in Java (Martin). This, however, seems to be 

 doubtful, since Verbeck and Fennema, 2 although they do not posi- 

 tively deny the possibility of the existence of Archaic rocks, pro- 

 nounce the schists of Java Cretaceous, upon which, unconformably, 

 Eocene and younger Tertiary beds are deposited. Archaic rocks 

 are found in the Island of Amboina, where they are overlaid by 

 Tertiary and Quarternary coral limestones. Between both there 

 are, locally, older sediments of undetermined age. 3 



Aside from the supposed Cretaceous schists in Java, we know of 

 beds of this period in Borneo, and, according to Kossmat (1895, 

 p. 469 f.), only such that belong to the Upper Cretaceous, corre- 

 sponding to the Ariyalur group (Senonian) of India. This fact is 

 the more important, since, as Kossmat points out, it demonstrates 

 that the Upper Cretaceous of southern India can be traced over 

 Assam and Borneo to Japan and the Island of Sachalin (and thence 

 to the western coast of North America). This indicates a contin- 

 uity of the oceans in this direction, and consequently Australia and 

 Asia must have been disco?inected in the Upper Cretaceous. 



From the foregoing, the conclusion may be drawn, that the 

 geology of the Indo-Malaysian Archipelago is roo scantily known to 

 form an adequate idea of the former connection of Australia and 

 Asia. This much, however, is settled, that large parts of this 

 archipelago were once land, and the single islands were in many 

 cases connected with one another. Verbeck (/.<:,) has shown that 

 of the Island of Java, in Miocene time (that is to say, very late), only 

 the western part existed as a unit, and that it was continued east- 

 ward by a series of small islands. At the end of the Tertiary these 



the Lias (Martin, ibid., Vol. 5, 1898; see also Molengraaff, G. A. F., Geolo- 

 gische Verkennigstochten in Central Borneo, 1900). 



1 Martin, ibid., Vol. 5, 1896. 



2 Geologiske beschryving von Java en Madera, 1 897. See also Verbeck, in 

 Petermanns geograph. Mitteil,, 1898. 



3 Martin, K., Reisen in den Molukken, in Ambon, aen Uliassem, Seran und 

 Burn. Geolog., Teil 1, Leyden, 1897. 



