POLYCYSTINA OF BARBADOES. 451 



cystina, mingled with Diatomacere, with a few calcareous Fora- 

 minifera, and w r ith calcareous earth which was probably derived 



FIG. 214. 



Fossil Polycystina, &c., from Barbadoes: a, Podocyrtis mitra; 6, Rhabdolithus sceptrum; c, 

 Lychnocanium falciferum; d. Enoyrtidium tubulus; e, Flustrella concentrica; /, Lychnocanium 

 lucerna; #, Encyrtidium elegans; h, Dictyospyris clathrus; i, Encyrtidium mongolfieri; fc, Stepha- 

 nolithis spiuescens; Z, S. nodosa; m, Lithocyclia ocellus; n, Cephalolithis sylvina; o, Podocyrtis 

 cothurnata ; p, Rhabdolithes pipa. 



from the decomposition of corals, &c., so as to form, according to 

 the relative proportions of these constituents (which differed in 

 different parts of the deposit), a tripoli-like sandstone, whitish 

 and very friable, a compact calcareous sandstone, and strata of a 

 marly character sometimes containing semi-opal. Previously to 

 this last discovery, which was made in the year 1846 (the mate- 

 rials having been furnished by the geological researches of Sir 

 R. H. Schomburgk), 39 species of Polycystina had been esta- 

 blished by Prof. E. ; but in the Barbadoes deposit, he has detected 

 no fewer than 282 forms which he considers to be specifically 

 distinct, besides 25 species of Diatomacese and Foraminifera, and 

 54 forms which he cannot distinctly determine, but which he 

 classes under the provisional designations of CreolitJiaria and 

 Phytolitharia, making 361 in all, of which more than 300 were 

 previously unknown. The 282 species of Polycystina are arranged 

 by Prof. E. in seven families, which include forty-four genera ; 

 but it is obvious that in our present state of almost entire igno- 

 rance of the structure and physiology of the animals to which 

 these shells belong, no classification can be otherwise than pro- 

 visional. Few Microscopic objects are more beautiful than an 

 assemblage of the most remarkable forms of Barbadian Polycys- 



