26a 
1 14 Bulletin 35 
Page 2yS 
Strata, their position and order of succession as well as their 
origin and organic contents were imperfectly elucidated ; and for 
part of this there is the excuse that it is exceeding!)' difficult if 
not impossible to obtain anything like clear evidence of super- 
position among the different beds or formations. It is usually 
by inference alone that we have to deduce the respective posi- 
tions and age of the beds. And in this of course there is liability 
to error. 
The tertiary rocks of Xaparima in Trinidad are described in 
the Report as a series of marls, conglomerates and calcareous 
sands. The Report mentions the cliffs of marl, the most im- 
portant exposure of the series, on the shore of the Gulf of Paria. 
These cliff's extend some distance north and south of the Town of 
San Fernando. After alluding to the extensive presence of 
asphalt in the beds, the Report states the existence of calcareous 
nodules, thin beds of limestone, and some sandstones, and refers 
particular!)' to a stratum to the south of the Town standing out 
into the Gulf and appearing at first sight like a vertical dyke of 
asphalt. This stratum is figured in the Report and the authors 
state that on examination they found it to be merely a highly 
inclined layer of marl with fragments of shells and a large pro- 
portion of bitumen. This is the bed referred to in my com- 
munication of July 1863* to the Scientific Association of Trini- 
dad as being entirely or almost entirely composed of the remains of 
Orbitoides and Nummulina. I referred to this bed again in 1866 
when I read to the Geological Society a paper on the relations of 
the Tertiary formations of the West Indies. Among the illus- 
trations to that paper was a diagram sketch of part of the coast 
section near San Fernando,! and Profes.sor T. Rupert Jones was 
good enough to append a note on the Orbitoides and Nummu- 
lince.+ I had indicated as unfossilferous certain other beds ex- 
posed in the coast section. The oolitic texture of these and others 
of the Xaparima rocks had been noted in the Geological Report, 
but apparently the exact nature of that texture had not oc- 
curred to the authors any more than it had to me when writing 
my paper of 1866. A subsequent and more careful examination 
showed me that the supposed oolitic grains were no other than 
minute fossils belonging chiefly to the order Foraminifera. 
I announced this discovery in a paper read before the Trini- 
dad Society in 1872 and published in the “Geological Magazine’ ’ 
for 1873. In it I gave the names of fifteen species of foraminifera 
besides those already recognized from the Orbitoides bed. Sub- 
sequently I published in the “Geological Magazine’’ (Sept, and 
*Reprinted in “Geologist,” 1864, page 159. 
tQuart. Journ. Geol. Soc. vol. xxii (1866) p. 571. 
jSee also Geol. Mag. vol. i, p. 102. 
