UJG THE VOYAGE OF H.M.S. CHALLENGER. 



Dimensions. — Diameter of the oviter shell 0-24, middle O'OG, inner 0'02 ; cortical pores 0007 to 

 0015, bars 0-004; length of the spines 0-12. 



Habitat. — Central Pacific, Station 274, depth 2750 fathoms. 



Subfamily Stauroceomyida,^ Haeckel, 1881, Prodromus, pp. 449, 453. 

 Definition. — S t a u r o s p h se r i d a with four concentric spherical lattice-shells. 



Genus 68. Staurocromi/umJ' Haeckel, 1881, Prodromus, p. 453. 



Definition. — ^Staur osp h aeri d a with four concentric lattice-spheres and four 

 crossed, equal, simple spines. 



The genus Staurocromyum has arisen probably from Stauracontium by duj^lication 

 of the cortical shell, two concentric shells lying within, two others outside the central 

 capsule. 



1. Staurocromyum quadruplex, n. sp. 



Eadial proportion of the four spheres:=l : 2 : 8 : 10. Both medullary shells with very small, 

 regular, circular pores. Inner cortical shell with regular, circular, hexagonally-framed pores, twice 

 as broad as the bars ; from each hexagon-corner arises a small by-spine, and these, connected by 

 tangential branches at equal distances from the centre, form the delicate outer cortical shell, with 

 spiny surface. Four main spines three-sided jiyramidal, as long as the shell radius. 



Dimensions. — Diameter of the four shells— (A) 025, (B) 02, (C) 005, (D) 0-025 ; length of the 

 spines 0-12. 



Habitat. — Central Pacific, Station 271, depth 2425 fathoms. 



2. Staurocromyum quadrispinum, n. sp. 



Eadial proportion of the four spheres = 1 : 3 : 9 : 12. Both medullary shells with small, regular, 

 circular pores. Both cortical shells with irregular, roundish pores. Surface covered with short, 

 conical by-spines. Four main spines cylindro-conical, somewhat longer than the shell diameter. 



Dimensions. — Diameter of the four shells — (A) 0-24, (B) 0-18, (C) 0-06, (D) 0-02. 



Habitat. — Central Pacific, Station 265, depth 2900 fathoms. 



Genus 69. Cromyostaurus,^ Haeckel, 1881, Prodromus, p. 453. 



Definition. — St aurosphserida with four concentric lattice-spheres and four 

 crossed, equal, branched spines. 



' Staurocromyida = Staurosphserida qnadruplicia=Tetrasph8erida tetracantha. 

 ^ S(aurocromj/Mm= Cross-onion ; ffrai/joV, x-^ofivot. 

 ' CromyostaUTUS = Omou-aois; xQofivov, arav^ii;. 



