606 MESSE8. W. HILL AND A. J. JUKES-BROWNE [Nov. 1 895, 



We can do no more than refer them to the family Astrosphaerida, 

 there being insufficient detail to place them in any particular genus. 



PL XXII. fig. 4 shows a circular outline enclosing comparatively 

 clear granular crystals of calcite ; periphery clear and unbroken. 

 No trace of medullary shell. Three primary spines arranged un- 

 symmetrically around the test. 



Diameter -35 mm. Length of spines *37 mm. 



Locality : Wilbury Hill, Hitchin. Horizon : Melbourn Rock. 



PL XXII. fig. 5 seems to be the same species, though the general 

 outline is less regular. Pive spines are seen, with the base possibly 

 of a sixth. Clear granular calcite occupies the place of the test. 

 No medullary shell. 



Diameter *27 mm. Length of spines -22 mm. 



Locality : Leagrave Road, Luton. Horizon : Melbourn Rock. 



PL XXII. fig. 7 resembles fig. 4. The test is filled with clear 

 granular calcite. Only one primary spine can be seen, though the 

 bases of three others can be made out. There are indications at 

 two or three points of secondary spines. There is also a distinct 

 ring occupying the position of the medullary shell in the centre of 

 the test. 



Diameter '48 mm. Length of spine '35 mm. 



Locality : Leagrave Road, Luton. Horizon : Melbourn Rock. 



(?) Family SxAraosPHiERXDA, Haeckel. 



Sphseroidea with a simple lattice shell traversed by four crossed 

 and equal spines in one plane. 



The two forms which we somewhat doubtfully refer to this family 

 have three spines, two opposite and one nearly at right angles. 

 We assume, therefore, that the fourth spine has either been broken 

 off, or did not come quite within the plane of the section. They 

 do not seem to agree either with the three-spined genus Spongotripus 

 of the family Spongodiscida, or with the three-spined forms of the 

 discoidal genus Triactiscus (' Challenger ' Report, pt. i. pp. 580 & 

 432). 



Riist figures a three-spined radiolarian from the coprolites of 

 Zilli (Staurocromyum Muelleri) 1 which resembles those we describe, 

 except that the pair of spines is not exactly opposite, though nearly 

 so. 



PL XXII. fig. 6 shows a circular outline filled with dense, 

 amorphous calcareous material, the outer portion marked by a com- 

 paratively wide belt of clear crystalline calcite, which is regularly 

 broken by alternate light and dark spaces, probably indicating a 

 shell with large pores. There are faint indications of a medullary 

 shell. Three spines visible, short, broken, the odd one not quite 

 equidistant from the other two. 



Diameter -18 mm. Length of spines "10 mm. 



Locality : Royston. Horizon : Melbourn Rock. 



PI. XXII. fig. 15 shows a circular cast, with clearly marked 



1 ' Palseontographica,' vol. xxxiv. (1888) p. 193, pi. xxiii. fig. 8. 



