HILL; GEOLOGY OF JAMAICA. 127 
duerdeni, The association together of species of Stylocenia and Stylo- 
Phora, both being close to -Eocene species of Europe, would make the 
Probability in favor of the Eocene age of the beds. Therefore the paleon- 
tologic evidence, though not conclusive, supports the opinion of Duncan 
regarding the age of the beds. Fortunately the stratigraphic position of 
the Richmond beds is clearly made out, independent of the fossils, so in 
this Case positive paleontologic proof is not essential for determining 
their position. We studied the locality of Port Maria from which these 
rals came in order to ascertain their stratigraphic position, which beyond 
doubt is that of the typical Richmond beds. 
Ethoridgo 1 mentions the occurrence of fossil Rudistes in these beds, 
ut Suggests in explanation that their presence might be accounted ‘for 
"pon the hypothesis that they could be water-rolled survivals of the 
“Mudation of the lower lying Cretaceous beds. Whether the specimens 
E Hippurites,” Radiolites, and Actxonellas noted are indigenous to these 
Particular beds or not, we cannot state, not having been so fortunate as 
9 find any of the fauna in situ. We question the conclusion, however, 
that they are derived specimens, because similar forms of Rudistes at 
“ist were found by us Zn situ in the overlying Cambridge beds, as will 
\ Shown presently. It is probable, as shown in the Ballard bed of the 
Minho section, that these Rudistean forms appeared in sporadic colonies 
Woughout the thickness of the black shales of the Minho and Richmond 
eds, and continued into the Cambridge formation. Whoever undertakes 
1 further study of these beds must remember that specimens of free and 
Nell proserved Rudistes should not be confused with the rolled pebble of 
urd crystalline limestone of the Jerusalem type which should also occur. 
` = presence of the supposedly Cretaceous Rudistean genera would 
rdin 
arily invalidate the data upon which the Eocene age of the Rich- 
“ond beds hitherto depended for establishment, were it not for our 
Positive evidence to be presented that these forms are found in situ in 
*Verlying beds, associated with undoubted Eocene fossils. The other 
Pecies aro all of Eocene facies and point to their Eocene age, which 
Co 4 d i 5 FR * 
Nelusion we are able to fix with positiveness by the evidence of the 
Over] 
i Ying Cambridge beds, where a similar mixture is found, whose true 
atu 
te has hitherto escaped observation. 
The Cambridge Formation. 
From a paleontologic standpoint these beds mark one of the most 
int , : i : à 
resting and valuable horizons in the whole Jamaican sequence, 
1 Jamaican Reports, p. 311. 
