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HILL: GEOLOGY OF JAMAICA. 135 



wise Eocene fauna, is a perplexing feature difficult of explanation. The 

 occurrence of Rudistes and Actseonella in the supposedly liichmond 

 Eocene beds of Jamaica, as recorded by the writers of the Jamaican Re- 

 ports, has already been noted. Tlieir 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 

 occurrence. 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 lamellae 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 Caprina 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 

 geologists,^ 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 Hall. 



Another fact which reinforces the supposition that the mixture of 

 these Cretaceous and Tertiary forms is natural is that the Jamaican 

 geologists originally described the rocks of the typical Cambridge beds 

 as "the Cretaceous or Hippurite limestone."^ In fact, we discovered 

 the Catadupa beds while making a vigorous search for the alleged Cre- 

 taceous beds which had been described as occurring between Chesterfield 



1 Jamaican Reports, p. 233. 



2 Ibid., pp. 245, 246. 



