50 DR. G. J. HINDE ON THE RADIOLAEIA IN THE [Feb. 1 899, 



Diameter of test, 0*105 mm. ; width of pores, 0*005 to 0-015 mm. ; 

 length of radial spine, 0*1 mm. ; of secondary spines, 0*01 mm. 

 In the specimen figured the radial spines are broken away, and 

 only their stumps remain ; but a complete spine, in position on 

 another specimen, is shown in the figure. In siliceous limestone. 

 No. 245 3. 



Heliosph^ea clayata, sp. nov. (PL YIII, fig. 28.) 



Framework of test delicate ; the pores are rounded or polygonal, 

 and unequal in size; there are four or five robust primary spines 

 shown : these taper very gradually, and terminate obtusely ; the 

 secondary spines are conical and pointed. Diameter, 0*075 mm. ; 

 width of pores, 0*0075 mm. ; length of primary spines, 0*1 mm. ; 

 thickness, 0*022 mm. In siliceous limestone. No. 245 3. 



Genus Heliosoma, Haeckel. 



The test consists of two latticed spheres (a cortical and a medul- 

 lary), with large radial, and smaller and more numerous secondary 

 spines. 



Heliosoma echinatttm, sp. nov. (PI. IX, figs. 1 & 2.) 



The cortical test has small lattice-pores ; the medullary test is 

 small, with very slender lattice-framework and polygonal pores ; 

 the larger radial spines are robust and gradually tapering, the 

 smaller are very numerous, slender needle-shaped, and unequal in 

 length. Diameter of cortical test, 0*16 to 0*22 mm. ; thickness of 

 wall, 0*015 mm. ; diameter of medullary test, 0*05 mm. ; length of 

 primary spine, 0*27 mm. ; thickness at base, 0*03 mm. ; secondary 

 spines, 0*02 to 0*1 mm. in length. Not uncommon. Occurs in 

 volcanic tuff. No. 387 d. 



Only sections of this form are as yet known, and in the specimens 

 figured one alone of the radial spines in each case is preserved, but 

 there are indications of the broken-off bases of others. The radial 

 spine of fig. 1 probably represents merely the central portion of 

 the spine ; it may originally have been equally as stout as that in 

 fig. 2. The medullary test is faintly shown in fig. 1, but cannot be 

 distinguished in fig. 2, which is infilled with somewhat granular 

 silica. Both the figured specimens occur in the same microscopic 

 section of the rock. 



Heliosoma Paeons, sp. nov. (PI. IX, fig. 3.) 



In its main features this form resembles the preceding, but the 

 pores of the outer test are circular ; the medullary test has not been 

 preserved ; the secondary spines are of a stout character, and there 

 is the lower portion of an unusually thick radial spine. Diameter 

 of test, 0*16 mm. ; width of pores, 0-01 mm. ; basal thickness of radial 

 spine, 0*04 mm. ; length of secondary spines, 0*11 mm. Pare. 

 In siliceous limestone. No. 245 3. Named in honour of Prof. 

 C. F. Parona, of Turin. 



