152 bulletin: museum of comparative zoology. 



the following fossil species from the beds at Bowden : Neocyclotus (Pty- 

 chocochlis) bakeri, Simpson ; Lucidella costata, Simpson ; Pleurodonte 

 bowdeniana, Simpson ; Thysanophora ; Opeas ', Succinea. 



In the marginal land derived material of the upper part of the Blue 

 Mountain Series and Cambridge beds, no remains of land or fresh water 

 mollusca have been found, and if they existed in late Cretaceous or 

 early Eocene times, it is singular that no trace of them can be found 

 in beds so peculiarly adapted for their occurrence. Even if they pre- 

 viously existed, their absence in the deep water marine beds of the 

 Montpelier and Moneague beds would be natural, for they are never 

 met with in such formations. 



In the Bowden series, however, land shells do appear for the first 

 time, several species having been sorted out of the great fauna of Fo- 

 raminifera, Bryozoa, Hydroids, corals, and Mollusca of this peculiar lit- 

 toral formation which occurs in the midst of the great White Limestone 

 Series. Their appearance here fits in beautifully with the facts of the 

 Mid-Tertiary land expansion elsewhere given, and thoroughly satisfies 

 the facts of the present known distribution of their descendants in other 

 islands and in Central America, as elsewhere explained. Simpson has 

 found a probably fossil land shell in the succeeding Cobre limestone 

 of Bog Walk. 



A few traces of fish teeth have been found in the Bowden formations. 



In resume, it can be said that the Bowden fauna as a whole marks 

 a most important horizon in Jamaican history, representing the reap- 

 pearance of molluscan life after the long hiatus intervening since the 

 Cambridge epoch, and presents the beginnings of the littoral fauna 

 which have since prevailed around the border of Jamaica in the later 

 Tertiary, Miocene, and Pliocene-Pleistocene, and recent time. 



The Cohre Beds. — The Cobre (White Limestone) which may be a 

 synchronous but deeper water formation than the Bowden beds, is 

 largely composed of Foraminifera mixed rarely with debris of MoUusks, 

 simple corals and Echinoidea. Mollusca are almost entirely missing 

 from this formation, except at its immediate base near Bog Walk village, 

 where many imperfect casts may be found, all of which have a super- 

 ficial resemblance to the Bowden and later forms. In these beds we 

 found two or three specimens of Echini. The main portion of this 

 limestone is almost entirely foram in i feral. 



Our microscopic sections of the white limestone of this formation, from 

 the convict quarry east of Kingston and Bog Walk, show a large num- 

 ber of small Foraminifera of many species, but in which Nummulina;, 



