794 REPORT—1896. 
to be full of the tests of Foraminifera associated with other organisms. This is 
deeply interesting, but it is at least equally so to know that in Palzozoic seas the 
condition of things was similar, The chalk has been spoken of as the Cretaceous 
equivalent of the calcareous ooze drawn up from the Atlantic of to-day, but the 
Carboniferous Limestone is very much older chalk. 
Another microscopic form of life which existed in great profusion on the floor 
of the Carboniferous sea is the remarkable genus Calcisphera. It consists of a 
hollow calcareous sphere averaging in diameter about ‘004 of an inch, and when 
cut in section has the appearance of a ring. In such numbers did this spherical 
object exist that we could scarcely section a small piece of limestone from the 
middle series of the Carboniferous Limestone without finding several specimens or 
fragments of Calcisphera. 
The author next referred to the encrusting organisms which lived in the Car- 
boniferous sen. The work was similar to that described in the Wenlock sea, 
and to such an extent had the encrusting been carried on that some beds of 
the Carboniferous Limestone are practically built up of the minute sphericles so 
produced. As, too, in the case of the Wenlock sea, the encrusting process was 
chiefly done by the genus Girvanelia, but there was also another encrusting 
organism at this period, namely, the genus Mitcheldeania, which was a more 
complicated form of life compared with Girvanella. 
Passing to the Oolitic system of the Jurassic period, the author pointed to 
the profusion of marine life which existed, but the point of interest to which he 
desired to especially refer was the formation of the oolitic granules, of which these 
rocks were chiefly constructed. 
Up to the time of the author’s investigations these granules were regarded as 
chemical concretions, but in the ‘ Geological Magazine’ of 1889 he showed that 
the larger types of oolitic granules, known as Pisolite, were not concretions but 
the work of organisms. He has since been forced to the conclusion that this 
organic origin applies to all oolitic granules, large and small. 
The author then referred back to the encrusting processes which took place 
on the floor of the Wenlock and Carboniferous seas for the purpose of pointing 
out that the granules so formed were really oolitic granules, In the Jurassic 
Oolite sea, however, the encrusting organisms had greatly increased, and they 
have been the chief builders of the oolitic rocks. The process was briefly this. 
As the fragmental remains of calcareous organisms settled on the floor of the 
sea they were seized hold of, so to speak, by the encrusting organisms which 
gradually inclosed them. At times nearly every fragment was so captured, 
and became the nucleus for the encrusting growth; in this way the Jurassic 
freestones were constructed. 
Further proof of the organic origin of oolitic granules has been produced by 
Rathplatz, who has shown that oolitic granules collected on the shores of the 
Red Sea and Great Salt Lake are the work of calcareous alge. This again 
bears out the truth of Hutton’s statements, that we are to understand the past 
by the present, 
2. The Rippling of Sand. By Vaucuan Cornisu. 
The author distinguishes three principal kinds of rippled sand, viz.— 
1, The Ripple Mark of Sea. 
2. The Ripple Mark of Streams. 
8. The Ripple Mark of Dunes. 
In (1) symmetrical, knife-edged ridges are built up, owing, as is well known, 
to the complete reversal of the current at short intervals, which results in an 
effective co-operation of the direct current with the vortex formed in the lee of 
projections of the rough surface of the sand. This mechanism in the vertical 
plane raises the ridges, and, in plan, extends them laterally, so that the mottled. 
surface of the initial stage is changed into long lines of parallel ridge and furrow. 
If the direction of the waves changes another set of ridges is formed, and this 
