REPORT ON THE RADIOLARIA. 167 



The genus Cromyostaurus differs from the preceding Staurocromyum, its ancestral 

 form, in the ramification of the four crossed spines. 



I. Cromyostaurus verticillatus, n. sp. 



Radial proportion of the four spheres = 1:3:11:13. Both medullary shells with small, regular, 

 circular pores ; inner cortical shell with regular, hexagonal pores ; from the hexagon-corners 

 arise small, radial by-spines, which at equal distances from the centre send out forked tangential 

 branches, three from each spine, and by communication of these form the outer, delicate, cortical 

 shell. Four main spines nearly as long as the shell diameter, three-sided prismatic, with four to 

 six verticils of ramified lateral branches, each verticil composed of three forked branches, which 

 ramify again. 



Dimensions. Diameter of the four shells (A) 0'26, (B) 0'22, (C) 0'06, (D) 0'02 ; length of the 

 spines 0'24. 



Habitat. Central Pacific, Station 268, depth 2900 fathoms. 



Subfamily STAUROCARYIDA, 1 Haeckel, 1881, Prodromus, pp. 449, 454. 



Definition. S taurosphserida with five or more concentric spherical lattice- 

 shells. 



Genus 70. Staurocaryum? Haeckel, 1881, Prodromus, p. 454. 



Definition. S taurosphaerida with five or more concentric lattice-spheres and 

 four crossed, equal spines. 



The genus Staurocaryum has arisen from the preceding Staurocromyum by the further 

 multiplication of the concentric spheres ; in the only observed form there are six, at 

 nearly equal distances apart. 



1. Staurocaryum arborescens, n. sp. (PI. 15, fig. 8). 



Shell composed of six concentric latticed spheres, at nearly equal distances apart, and with 

 somewhat regular, circular pores, the size of which gradually increases from the first to the sixth 

 shell. The surface of the outermost shell is densely covered with numerous arborescent by-spines, 

 which bifurcate from three to four times, and are three-sided pyramidal at the base, and twice as 

 long as the distance between each two shells. The six shells are connected only by four crossed, 

 conical, radial beams, which increase in diameter from the centre, and are prolonged outside into 

 very stout cylindrical, radial spines, irregularly covered with small thorns and forked ramules, and 

 nearly as long as the shell diameter. Only a single specimen was observed. 



' Staurocaryida = Staurospha}rida multiplicia=Polysphaerida tetracantha. 

 2 Staurocaryum, = Cross-nut; <nuvt>6s, xafi/o*. 



