HILL: GEOLOGY OF JAMAICA. 135 
Vise Eocene fauna, is a perplexing feature difficult of explanation. The 
Occurrence of Rudistes and Acteonella in the supposedly Richmond 
Eocene beds of Jamaica, as recorded by the writers of the Jamaican Re- 
Ports, has already been noted. Their unsubstantiated hypothesis that 
these might be rolled survivals of the lower beds naturally originates 
the inquiry if the Rudistes of the Catadupa beds may not be of similar 
Occurrenco. The writer can find no foundation for such an hypothesis 
in case of the Rudistes in the Catadupa beds. Many of the specimens 
collected were independent or unattached, resembling in appearance the 
free forms found in the higher occasional horizons of the Minho beds. 
The single specimens show no signs of having undergone attrition by 
rolling. The delicate lamelle and corrugations, such as would be 
broken by the least possible attrition, are all preserved, as well as the 
Soft chitinous structure of some of the species like Oaprina jamaicensis, 
Whitfield. In fact, these forms show no evidence whatever of having 
undergone such treatment, and are much better preserved than any 
found in the Jerusalem beds of undoubted Cretaceous origin. In ad- 
dition to the loose or free specimens, there was a solid stratum two 
feet in thickness made up of an agglomerate of these shells as thick as 
Coral heads in reef rock, and absolutely in situ. Furthermore, it is 
difficult to see how such forms, if rolled, could have been sorted out 
And thus segregated without being accompanied by some of the hard 
enduring igneous pebble of the conglomerate beds of the Minho and 
Richmond formations, with and below which the lower Rudistes horizons 
are interbedded. 
Elsewhere the lithologic resemblance of the supposedly undoubted 
Cretaceous beds to the Yellow Limestone has been noted by the Jamaican 
Seologists,! and other fossils collected by us from the Minho River sec- 
tion are lithologically and specifically identical in every appearance with 
those of the Cambridge beds, including two of the typical Cambridge 
corals, also occur in the Rudistean Cretaceous beds of Logie Green and 
Trout, H all. 
Another fact which reinforces the supposition that tho mixture of 
these Cretaceous and Tertiary forms is natural is that the Jamaican 
Seologists originally described the rocks of the typical Cambridge beds 
*8 “the Cretaceous or Hippurite limestone.”* In fact, we discovered 
the Catadupa beds while making a vigorous search for the alleged Cre- 
%eous beds which had been described as occurring between Chesterfield 
1 Jamaican Reports, p. 238. 
2 Ibid., pp. 245, 240. 
