FOSSIL POLYCYSTINA. 



525 



Ehrenberg in the Chalks and Marls of Sicily and Greece, and of 

 Oran in Africa, and also in the Diatomaceous deposits of Bermuda 

 and Richmond (Virginia) ; but a large proportion of the rock that 

 prevails through an extensive district in the island of Barbadoes 

 has been found by him to be composed of Polycystina, mingled 

 with Diatomacea?, with a few calcareous Foraminifera, and with 

 Calcareous earth which was probably derived from the decom- 

 position of Corals, &c. 



Fig. 270. 







mm. 



$$kl^l / 



jS^s&Sa 



°W^- :J MM^ J 





' i i 



Fossil Polycystina, &c, from Barbadoes : — a, Podocyrtis mitra; 

 b, Rhabdolitkus sceptruin ; c, Lycbnocaniurn falcif eruni ; d, Eu- 

 cyrtidiuni tubulus ; e, Flustrella concentrica ; /, Lycbnocaniurn 

 lucerna; g, Eucyrtidium elegans; h, Dictyospyris clathrus ; i, 

 Eucyrtidium Mongolfieri ; k, Stepbanolitkis spinescens ; I, S. 

 nodosa ; m, Lithocyclia ocellus ; n, CephalolitMs sylvina ; o, 

 Podocyrtis cothurnata ; p, Rnabdolitbus pipa. 



403. Few Microscopic objects are more beautiful than an assem- 

 blage of the most remarkable forms of the Barbadian Polycys- 

 tina (Fig. 270), especially when seen brightly illuminated upon a 

 black ground ; since (for the reason formerly explained, § 86) 

 their solid forms then become much more apparent than they are 



