326 



PAL/EONTOLOGY 



last genus is very abundantly represented on modern 

 coral beaches. 



Of the Arenacea the most important are Saccammina 

 (Carb.-Rec.) of one or several spheroidal chambers ; 

 Endothyra (Carb.-Trias.) resembling some of the Rotalidae 

 in form ; and Orbitolina (Cret.) conical, the chambers 

 cyclical in arrangement. Textularia is commonly in- 



FIG. 99. LEPIDOCYCLINA TOURNOUERI, DOUVILLE AND LEMOINE, 



OLTGOCENE. 

 (Megalospheric form.) 



a, Vertical section. ( X 13.) b, Part of horizontal section. ( X 18.) 

 (After R. Douvilld and Lemoine.) 



eluded among Arenacea, but is always perforate and 

 hyaline, at least in early life. 



The Perforata are usually well-preserved fossils, 

 whether in Limestone or Clay, or even in sands in some 

 of the latest formations. The Imperforata, having 

 aragonite tests, are less frequently preserved. A very 

 special mode of preservation is that of internal casts in 



