1908-9. ] THE GEOLOGICAL CONNEXIONS OF THE CARIBEAN REGION. 383 
irrecognizable casts of molluska and other fossils. In one bed near 
Hillside I found Polystomela craticulata, This bed contains many 
subangular grains of quartz, and I found a small piece of pumice also. 
My friend, Mr. Earland, says of the foraminifer: “ This is Polystomela 
craticulata without doubt. It is a very variable species, but always 
easily recognizable. The specimens are of the thick subglobular variety 
and closely resemble those from Perim.”’ Brady (Chal. Rep., page 739) 
remarks that P. craticulata inhabits the shallow water of tropical and 
subtropical seas and ranges southwards from the Levant to the shores 
of Australia. It isnot known in the Atlantic nor as a fossil species. Its 
presence as a fossil in the miocene strata of Jamaica is therefore 
comparable with that of Planorbulina larvata and Pulvinulina favus in 
Trinidad. 
The yellow limestone with casts of molluska is obviously a distinct 
formation from the white limestone with foraminifera and radiolaria. 
This is again divisible into two, one which might be called a globigerina 
rock and the other of a more chalky texture, a radiolarian rock. The 
yellow limestone was probably formed in water up to and about one 
hundred fathoms in depth, while the true white limestones are deep sea 
deposits. The radiolarian rock is extensively developed in the neighbour- 
hood of Buff Bay on the north coast of Jamaica. It is a white material, 
not unlike the English chalk, and of nearly the same colour and consist- 
ence. It is composed almost entirely of globigerina and _ radiolaria. 
A similar limestone to this white chalk occurs in Cuba, as described 
by Hill (Bull. Mus. Harvard, 1895, page 253). Here it underlies the 
yellow limestone, similar to that identified by Dall as miocene in 
Jamaica. 
According to Tipenhauer (quoted by Hill, Geology of Jamaica, page 
181) a similar rock occurs also in Haiti (see Journ. Geol. Soc., Lond., 
1892, page 219). 
Near Buff Bay (Orange Bay) in Jamaica, I found two very interest- 
ing deposits, but I failed to make out their relationships to the 
radiolarian rock. The first of these I have termed orbulina rock. This 
does not seem to be a separate formation, but a local and subordinate 
part of the oceanic series. After washing off the finer particles a sample 
of this rock gave about 60 per cent. of Orbulina and about 30 per cent. of 
Globigerina. Among the remainder I detected the following foraminifera 
in addition to Globigerina and Orbulina 
