272 NATURAL SCIENCE. Oct.. 



We are further led to inquire whether there are any other regions 

 where similar assemblages occur, in which old Cretaceous species 

 are still found to play an important part. The greatest interest 

 undoubtedly attaches to Raine Island, off the north coast of Queens- 

 land, near the Torres Straits, owing to the fact that this is the only 

 locality where, at a depth of 155 fathoms, Tritaxia tticarinata, so 

 common in the Chalk Marl, is known to exist at the present day. In 

 addition, the presence of the delicate Spiropleda annectens, of Gaiidvyina 

 fugosa, and Ffondicularia archiacana — all Cretaceous species — shows 

 that this is not a mere isolated occurrence, but represents another 

 example of the preservation of Cretaceous forms under certain special 

 conditions. An examination of the geographical position of this 

 island likewise demonstrates that it lies not far from the south- 

 eastern boundary of a region of insular development, which includes 

 New Guinea, Borneo, etc. It is also on the northern boundary of 

 the Australian continent, and, further, its climate is of a distinctly 

 subtropical character. It is therefore significant that, although so 

 far removed from one another, we should find these two localities to 

 have these remarkably striking features in common, and at the same 

 time to possess between them some of the principal arenaceous species 

 occurring in the lower part of the Upper Cretaceous beds. 



The general resemblance of these localities to probable early 

 Upper Cretaceous conditions will at once be obvious. The materials 

 of the Chalk Marl and Upper Greensand appear to have been derived 

 from the western regions of our own island, so that it may be fairly 

 argued that these deposits were laid down on the eastern boundary 

 of a land, if not of a continental, area. Few will be inclined to 

 dispute that the result of the Cretaceous depression would be the 

 production of a number of insular areas, and there is much evidence 

 to support the theory of the existence of a sub-tropical climate at that 

 period. 



Hitherto no sharp delimitation of distribution has been attempted 

 by writers on this subject. The Foraminifera obtained from the 

 various zones of the Upper Cretaceous have been dealt with en bloc, 

 and but little attention has been paid, or reference made, to variations 

 arising from physical alterations, bathymetric or otherwise. 



The result of a preliminary study of the zones in definite order 

 has led me to the conclusion that this wide classification tends to hide 

 many interesting facts, and that, in order to arrive at a more complete 

 understanding of the subject, such questions as quantity, size, specific 

 abundance, position in the stratigraphical scale, and the character of 

 the rocks in which the forms occur, must all be carefully noted, 

 observed, and compared with the existing fauna and the general 

 sequence as displayed at the present time. ' 



For example, foraminiferal distribution depends, in many im- 

 portant particulars, on physical characters. The arenaceous species, 

 more especially the coarser varieties, build up their tests of sand- 



