169 
Guppy Reprint 
2 1 
Page 41 
and there are also specific affinities with the other ter- 
tiaries of the Island, as mentioned in Sec. 2 . But it 
does not seem, from the lists* given by the Geological 
Survey, that there is, anywhere, as far as has been dis- 
covered, the same assemblage of species. The number 
of recent forms in the beds under consideration forbids 
us however to assign an older date than the “upper 
part of the New' Parian’’ to them ; and further, the 
shells from the deposits described in the Geological Re- 
port do not possess that feature of diminutiveness w'hich 
is so remarkable in the Matura fossils. The ark found 
so abundantly in most of the Tertiary deposits of this 
Island {Area incongrua') seems to be absent from the 
Matura beds. Further researches will be required to 
show how far .some of the species of arctic types now 
existing in the West Indian seas may have commenced 
their existence in the tropics from the date of the sup- 
posed glacial influence. 
There is a ferruginous conglomerate at Saline Bay, 
.some little di.stance north of the Matura deposit, w'hich 
may possibly belong to the same period as the latter ; 
but it seems to be unfosssiliferous. 
6 . — Concluding Remarks. 
The facts relative to the Matura Deposits ma}' be of 
great interest and importance when our knowdedge shall 
have been far enough advanced to enable us to pronounce 
with some degree of certainty on the physical changes 
of this part of South America in late geological epochs. 
There is a great deal to be done in this respect. Be- 
fore any set of conclusions can be established firmly, 
the observations on w'hich they hav'e been founded must 
be confirmed b}' prolonged investigation. There is, 
however, an intere.st of its own attaching to the explo- 
ration of our later tertiaries, and w'ith regard to the 
Matura deposit, I may quote the very appo.site remark 
of Mr. Smith, of Jordanhill, “as it belongs to one of 
“the first steps in the descending series, every circum- 
*Report on the Geology of Trinidad p. 163-6. 
