"Vol. 56.] UPPER CHALK AT COULSDON. 697 



Triloncse sp. (PI. XXXVII, fig. 4.) 



Diameter of cortical test = -13 mm. Thickness of wall = about *02 

 mm. The surface of this specimen is crusted over, and the medullary 

 sphere is very obscure : this is about *06 mm. in diameter. Spines 

 small, prismatic. 



Genus AcantkospHjEra, Ehrenberg. 



The test is a simple latticed sphere, with eight or more radial 

 spines of the same kind. 



Acantsospsjeba sp. a. (PL XXXVII, fig. 5.) 



Test with large hexagonal pores. Diameter of test ='155 mm. 

 Spines imperfect, prismatic. 



AcANTKOSPHJERA Sp. j3. (PI. XXXVII, fig. 6.) 



Small test, with large hexagonal pores. Diameter = *115 mm. 

 Spines imperfect. 



Order PRUNOIDEA, Haeckel. 



Genus Litsapium, Haeckel. 



The test is a simple latticed shell, with a radial spine at one pole. 



Litsapium sp. (PI. XXXVII, fig. 7.) 



Test small: long diameter =-105 mm.; transverse diameter 

 = •09 mm. Radial spine reduced to a stump. Pores uncertain. 

 Surface-markings probably due to corrosion. 



Order DISCOIDEA, Haeckel. 



Genus T&eodiscus, Haeckel. 



Test a simple lenticular latticed shell, with three radial spines 

 extending from the margin, at equal or unequal distances apart. 



Theodiscus sp. (PL XXXVII, fig. 9.) 



Test a circular flattened disc. Diameter = "225 mm. Spines 

 prismatic and apparently serrated ; one missing. Length ='08 mm. 

 Markings secondary. 



Genus Spongotripus, Haackel. 



Test discoidal, of porous, reticulate, or spongy framework, with 

 three solid radial spines on the margin. 



Spongotripus pauper (?) Rust, (PL XXXVII, fig. 10.) 



Test triangular in outline, with slightly concave sides. Surface 

 rough and obscure. Length of test without spines = -23 mm. ; 

 breadth ='175 mm. Length of spines (not quite perfect) = *15 mm. 



This is probably identical with Sp. pauper, Rust, figured in ' Pake- 

 ontographica ' vol. xxxiv (1888) pi. xxvi, fig. 3. 



