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68 BULLETIN: MUSEUM OF COMPARATIVE ZOÖLOGY. 
they are as a whole of coralline or coral reef origin, as has also been 
shown by a few hand specimens collected without reference to horizon 
and sent to England, studied by specialists, who recognized them as 
being of foraminiferal composition. 
Not the least important result of our researches will be a demonstra- 
tion that the larger thicknesses of these limestones are neither of mollus- 
can, coralline, or reef rock origin, but are foraminiferal oceanic deposits 
and other offshore calcareous oceanic muds composed of organic detritus 
laid down at depths below that at which reef rocks were formed and in 
periods of geologic time prior to the appearance of the modern reef 
building species in the sequence. 
The white limestones of Jamaica, both of the Oceanic and Coastal 
Series, are various manifestations of the vast agency in past times of 
animal life as extractors of carbonate of lime from sea water, similar to 
what is now going on throughout the warm regions where the oceanic 
waters are comparatively free from land sediment. That white lime- 
stones, entirely distinct from true reef rock, are now being formed 
throughout the tropios is a matter of common observation. Wherever 
calcareous organisms abound around the margins of shores uncontami- 
nated by land débris, the beach wash of caleareous material is rapidly 
cemented by its own solutions into white limestone rock of various 
textures; shells into coquina; shell débris and corals into “ oölite,” 
which, when wave washed and sea sprayed, like surfaces of the ele- 
vated reefs, indurate into hard partially erystallized surfaces. In addi- 
tion to the near shore deposits, as shown by A. Agassiz and others, 
calcareous muds of foraminiferal origin are being formed to depths 
of 5,000 feet or more. When elevated into land these form white 
limestones. 
It is also apparent that white limestones may be partially coralline, 
as attested by well preserved coral remains, and yet not necessarily of 
coral reef origin, or in any manner connected with reef making phenom 
ena, All stony corals are not reef builders, and many solitary forms 
such as are found in some of the White limestones, inhabit oceani? 
water to a depth of 1,000 fathoms below the zone of 100 fathoms 
below which true reef building corals do not live. Yet it has been 
customary to call any limestone with sparse traces of these solitary 
corals “coralline,” and from this it was easily transposed into coral reel 
rock. 
In general the tropical white limestones may originate in several 
ways, as shown in the following table, 
