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



outer pores, like the five petals of a fiower. Medullary shell half as broad as the inner cortical shell, 

 with regular circular pores. 



Dimensions. — Diameter of the outer shell 0'25, middle 02, inner O'l ; outer pores on an average 

 0-006, middle 0-012, inner 0-004. 



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



Subfamily Ceomyosph^rida,^ Haeckel, 1881, Prodromus, pp. 449, 453. 



Definition. — L iosphserida -with four concentric spherical latticed shells, united 

 by radial beams. 



Genus 23. Cromyosphcera,'^ Haeckel, 1881, Prodromus, p. 453. 



Definition. — L iosphserida "with two intracapsular (medullaiy) shells and two 

 extracapsular (cortical) shells ; the former united with the latter by radial beams 

 piercing the wall of the central capsule. 



The genus Cromyosphcera is the only known genus of Cromyosphserida, or of such 

 Sphseroidea, the smooth shell of which is composed of two medullary and two 

 cortical shells. There may possibly be other Cromyosphserida, in which the shell is 

 composed of one simple medullary and three cortical shells, or only of four extra- 

 capsular cortical shells ; but such have not as yet been observed. 



1. Cromyosphcera quadruplex, n. sp. (PI. 30^ fig. 9). 



Radial proportion of the four spheres = 1:2:4:5. Outer cortical shell smooth, with large 

 regular hexagonal pores, ten times as broad as the bars ; inner cortical shell with irregular poly- 

 gonal pores, five times as broad as the bars. Both medullary shells with regular circular pores of 

 the same breadth as the bars. 



Dimensions. — Diameter of the four spheres — (A) O'lG, (B) 0-12, (C) 0-06, (D) 0-03. 



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



2. Cromyosphwra rosetta, n. sp. 



Radial proportion of the four spheres = 1 : 2 : 8 : 10. Outer cortical shell smooth, with regular 

 hexagonal pores and very thin bars ; inner cortical shell with the same number of exactly 

 corresponding, regular circular, hexagonally framed pores, twice as broad as the bars ; the corners 

 of the outer and inner hexagons united by radial bristles. Both medullary shells with regular 

 circular pores, twice as broad as the bars. 



Dimensions. — Diameter of the four spheres — (A) 02, (B) 0-16, (C) 0-04, (D) 0-02. 



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



1 Cromyosphteri(la = Liosphoerida tetraplicia = Tetrasph£erida anacantha. 

 ^ Croviyosphcera = Onion-sphere ; x^i/z-vov, a(puhcc. 



