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



Dimensions. Diameter of the outer shell 0'24, middle 0'06, inner 0'02 ; cortical pores 0-007 to 

 0-015, hars 0'004 ; length of the spines' 012. 



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



Subfamily STAUROCEOMYIDA/ Haeckel, 1881, Prodromus, pp. 449, 453. 

 Definition. S taurosphaerida with four concentric spherical lattice-shells. 



Genus 68. Staurocromyum, 3 Haeckel, 1881, Prodromus, p. 453. 



Definition. S taurosphaerida with four concentric lattice-spheres and four 

 crossed, equal, simple spines. 



The genus Staurocromyum has arisen probably from Stauracontium by duplication 

 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 = 1 : 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 pyramidal, as long as the shell radius. 



Dimensions. Diameter of the four shells (A) 0'25, (B) 0'2, (C) 0'05, (D) 0'025 ; length of the 

 spines 012. 



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



Dimensions. Diameter of the four shells (A) 0'24, (B) 018, (C) 0'06, (D) 0'02. 



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



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



Definition. Staur osphaerida with four concentric lattice-spheres and four 

 crossed, equal, branched spines. 



1 Staurocromyida=Staurosphasrida quadruplicia=Tetrasphserida tetracantha. 

 1 Staurocromyum Cross-onion ; <rrai/joV, 

 * Crornyostaurus = Onion-cross ; 



