CONTRIBUTION TO THE PALEONTOLOGY OF TRINIDAD. 27 



cardinal area). It also shows a divergence of the west coast species from a 

 common Antillean stock from which it migrated westward before the rise of the 

 isthmus. For this short, high form of Noetia is characteristic of the east coast 

 Oligocene. After that period they died out, but the western colonies have con- 

 tinued on to the present. 



Mactra austeniana adds a further indication of the Oligocene age of the 

 deposit. Typical Mactras, of which this is one, are not known in America from 

 formations older than the Oligocene. 



Pholas mackiana resembles both the recent east coast P. campechensis 

 Gmelin and P. chiloensis of the Peruvian shores. These species are surprisingly 

 alike, possibly even identical. This fossil Pholas from Brighton may well be 

 their common ancestor. 



Judging from all the above indications, the age of the shelly asphalt on the 

 Brighton beach is Oligocene — and late Oligocene, perhaps about equivalent 

 to the Chipolan of Florida. 



A yellowish-brown ferruginous bed outcrops on the southern main road, just 

 south of Pitch Lake, Brighton, near the 56% Mile Post. It is stratigraphically 

 below the asphaltic beds above described and stratigraphically above the large 

 Ostrea horizon of the Union Estate, Brighton. 



The fossils in the ferruginous bed are all in the form of casts, the original 

 substance of the shells having been wholly dissolved away. The majority 

 could not be determined. A few forms retained some traces of distinguishing 

 characters. These were : 



Area (Cunearca) chemnitzioides n. sp. 

 Area two sp. indet. 



Cardita (Carditamera) Virginia; n. sp. 

 Corbula sp. indet. 

 Martesia oligocenica n. sp. 

 Terebra sp. indet. 

 Oliva trinidadensis n . sp . 

 Purpura sp. indet. 

 Murex cf . domingensis Sby. 

 Calyptroea centralis Con. 



The known species, Calyptroea centralis, has never been found in strata 

 earlier than the Chipolan of Florida, hence its presence suggests that the bed 

 is not older than late Oligocene. 



The fragmental cast of Murex may be domingensis. If so this also indicates 

 Upper Oligocene. To this the evidence of the most abundant species of the 

 fauna of the ferruginous bed, Area (Cunearca) chemnitzoides , may be added. 

 Areas of this type with high umbones and a short, high form are not known 

 below the Oligocene on the southeastern coast of the United States and in the 

 Antilles. 



