30 ? 
Guppy Peprint 
159 
There are plenty of soils in the Couva district and neighbour- 
ing parts which would be improved by the addition of this fossil- 
iferous rock. As a road material it may serve in default of bet- 
ter, but it would not be of any great durabilitj-, and could not 
stand heavy traffic. 
I endeavored without success to obtain some information as 
to dip and strike and the relations of the bed to other beds in the 
neighbourhood. There was a kind of false bedding which ob- 
scured the real relations of the strata — but as no other beds were 
visible above or below I could not ascertain anj- other facts. 
Still in order to exhibit the relations of the strata I subjoin a di- 
agram which I hope will assist in making the general relations 
clear. This shows that the Couva and Montserrat miocene shell 
deposits were in course of formation at the same time as the lat- 
ter part of the oceanic deposits. The sub.sequent folding disloca- 
tion and upheaval have altered the apparent relations of the 
formations. Until we know' the ground better, and have detailed 
information as to the outcrop, &c. , of the geological formations 
we cannot give a more definite Section than this approximate 
one, w'hich is only diagrammatic. 
Page 3 
The terms Eocene Miocene and Pliocene were originally 
fixed by Lyell for the three great divisions of the tertiary strata 
(see Principles of Geology 8th Ed. page 177 ; Elements 6th Ed. 
page 187 ; and Student’s Manual 1878 page 122) in accordance 
with the percentage of recent species found in the formations so 
de.signated. The percentage test though fundamentally a useful 
one is not always free from difficulty in its application to partic- 
ular cases, and the We.st Indian miocene formation is one of these 
cases. And this arises in some degree from the fact that the 
proportion of recent species varies wdth each ob.server. Accord- 
ing to the list of names I give, amounting to about a hundred 
species, there are not more than three or four still-existing spe- 
cies in our miocene beds, and even these can easily be disposed of 
bj- giving them other names which in most cases are ready to 
hand. When we come to examine the shells we find a large 
