50 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Feet. 



8. White limestone with Acteeonella 40 



7. White limestone slightly yellowish 25 



6. Yellow marl alternating with limestone 50 



5. Purple shale in yellow limestone and marl 15 



4. Red " Trappean " conglomerate 6 



3. Yellow marls with limestone lumps and gigantic Caprinas . 29 



2. Three feet layer of limestone with giant Caprinas .... 67 



1. Yellow clays and limestones 23 



Xos. I., II., III., and lY. of the foregoing sections are undoubtedly of 

 later age than V., and owe their present lower topographic position to 

 faulting or later unconformable deposition. It is interesting to note 

 that the gigantic species of Rudistes occurs at the base of this section in 

 bed V. 2, — a low position apparently persistently maintained through- 

 out the island. 



It is unfortunate that here the relations of the fossiliferous formations 

 to the other beds of the Blue Mountain Series are concealed. 



It might be supposed that the yellow clays at the top of the Jeru- 

 salem section represent the horizon of similar material elsewhere widely 

 separated from the lower limestones by vast beds of tuffs and igneous 

 conglomerates. The paleontologic data do not demonstrate this con- 

 clusion, the fossils of the Jerusalem clay beds (Pholadomya and Ostrsea) 

 not l)eing found at other localities, nor are some of the smaller species 

 of Rudistes of probably higher horizons found here. Outcrops of 

 "Cretaceous limestone" 500 feet thick in St. Thomas-in-the-Yale,^ and 

 300 feet thick in Port Royal,^ are also recorded, but the writer has not 

 seen them. 



It is barely possible that a locality in Portland, mentioned by 

 Barrett,* may represent the upper clay horizon. This was described as 

 " a sandstone conformable with a thick bed of clay containing Hamites, 

 Baculites, Trigonia, and Pholadomya." This reference is the only 

 mention of the first three fossils from Jamaica. 



Near Bath, at the eastern end of the island, Cretaceous limestones are 

 exposed in the elevated structure near the southern base of the moun- 

 tains. This is the locality from wliich the Cretaceous of Jamaica was 

 first described by Barrett, who published a figure of the section.* The 

 principal formation of this vicinity is the ^Finho beds (Trappean of 



^ The Crotacooiis of St. Jnnios, as described by Sawkins (Jamaican "Reports, p. 

 246) is the Canibridjje formation of tliis paper. 



2 Jamaican Reports, p. 138. « Ibid., p. f2. * Ibid., p. 77. 



