72 



Ovulites. A stony, free, oviform, or cylindrical, poly- 

 pifer ; hollow within ; the extremities generally perforated, 

 and minute pores regularly diffused over the surface. 



Known only as a fossil ; very small, not exceeding two 

 millimetres in length. 



The openings are suspected to have proceeded from 

 inj ury . Grignon. 



Sp. 1. 0. margaritula. Oval, with very minute pores. Grignon. 

 2. 0. elongata. Cylindrical ; the extremities truncated. Ibid. 



Lunulites. A free, stony, circular polypifer, with one 

 side convex, the other concave. 



The convex side striated in rays, with interstitial pores ; 

 the concave side radiated with diverging rugae and grooves. 



Sp. 1. L. radiata. The concave side with radiating striae, the con- 

 vex with pores. 

 Fossil. Grignon. 

 2. L. urceolata Cupola-formed, the convex side latticed with 



numerous pores. 



It resembles in form the cup of an acorn or a thimble. 

 Fossil, from Parnes and Liancourt. 

 It is also found in the green sand of Wiltshire. 



Orbulites. A free, circular, stony polypifer ; flattish ; 

 porous on both sides, or at the margin ; resembling the 

 nummulites. 



Set with minute pores, sometimes scarcely visible, re- 

 gularly disposed, but not in a spiral order. 



It differs from Lunulites in having pores on both sides. 



1. 0. marginalis With a porous margin ; both sides flat. 



Recent. 



2. complanata. Thin, fragile, flat and porous on both sides. 



Fossil. Grignon; Guettard,Mem.iii, p. 434, Tab.xiii. fig. 30, 32. 



3. lenticulata. Upper surface convex, the lower flattish. 



Fossil. 



4. concava. Convex on one side and concave on the other ; 



surface rather rugous. 

 Fossil. 



