1864.] DUNCAN AND AVAL! JAMAICA. 13 



Jamaica is separated from its known equivalent formations by the 

 Atlantic, and that those which, according to the ordinary rules of 

 palaeontology, must be associated with it, as regards contemporaneity 

 and relative position, are the Hippurite-Mmestone of North Africa 

 (in the Province of Constantine, for instance) ; that of Portugal at 

 Alcantara ; that of Spain in Leon ; that of South- Western and South- 

 Eastern Prance, in the Departments of Lot et Garonne, Charente 

 Inferieur, Loire et Cher, Aude, Bouches du Rhone, Vaucluse, and 

 Var ; and that of Austria, at Gosau and Piesting. The English 

 Lower Chalk belongs to a special natural-history province, and 

 doubtless is of the same age as the Jamaican, due regard being 

 allowed for the limits of the notion of geological contemporaneity. 

 The discovery of forms common to Europe and the West Indies in 

 the Cretaceous strata fui^nishes another to the many examples of 

 the wide dispersion of species which occurred formerly; and it is 

 interesting to observe that the genera so well represented in the 

 Lower Chalk are equally well represented in the present Caribbean 

 Sea. The brainstone-corals, the stony compound corals, and the 

 porose Porites are the commonest in the reefs around the Antilles, 

 and their near allies appear to have luxuriated at Gosau and 

 amongst the French Hippurites. When the dependence of coral-life 

 on very definite physical conditions is considered (and there are few 

 scries of facts better made out than those which illustrate that 

 dependence), the identity of climate, purity of sea-water, absence 

 of fresh water, and equivalent depth of sea between the old chalk- 

 reefs and the modern are forcibly suggested. 



The Eocene shales and dark-coloured sands which represent the 

 conglomerate in some localities, or which constitute its upj)er part 

 in others, yield corals in no very great number. The specimens 

 from Port Maria are either dark and carbonaceous-looking, or are 

 encnisted on a fine dark-purple conglomerate : all are very significant 

 of the horizon, and recall the puny development of the species of the 

 London Clay. The Paracyathus from Yallahs valley resembles that 

 of the London Clay, being even stained black, like the Sheppey 

 specimens : the Stylocoenia emarciata is a well-known form in British, 

 Erench, Itahan, and Sindian early Tertiary collections, and the 

 Stylopliora contorta also. The Stylocoenia and Stylopliora are charac- 

 teristic Corals, and denote an Eocene horizon ; and they indicate, 

 when unaccompanied by other species, the existence of physical con- 

 ditions not favourable for coral-growth. 



The existence of strata of Eocene age in Jamaica was asserted by 

 the late Mr. Barrett, and their jiosition was marked on his diagram 

 of the succession of the strata of the island ; but it does not appear 

 that he has communicated any reasons for thus naming the plant- 

 bearing and other dai'k shales subordinate to the Miocene sands and 

 shales, except those referring to stratigraphy. That he was correct 

 there can now be no doubt, and an important member of the Tertiary 

 series is thus added to the formations represented in the West Indies. 

 Its equivalents are as yet unknown in the other islands ; but it is not 

 probable that a great conglomerate resembling the Flysch in magni- 



