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



verticil) ; by further ramification and communication of tliese brandies tlie triangular net-plates 

 arise, filling out the sides of the octahedral cortical shells. Diameter of all shells little 

 different. The outer free parts of the six spines are arborescent, twice to three times as long as the 

 enclosed inner parts, and bear six to eight verticils of free lateral branches, decreasing in size 

 towards the distal end (similar to Arachnosphccra). 



Dimensions.— Diameter oi the six sheUs— (A) 0-015, (B) 0-04, (C) Ol, (D) O'lG, (E) 0-22, (F) &c. ; 

 average distance of the concentric octahedral 0-06 ; length of the radial spines O'S to 0-4 and more, 

 breadth 0-02. 



Habitat. — Central Pacific, Station 274, surface. 



Subfamily Hexadorida,^ Haeckel, 1881, Prodromus, pp. 449, 455. 



Definition. — C u b o s p h re r i d a with spongy spherical or octahedral shell (with or 

 without enclosed concentrical lattice-shells). 



Genus 85. Cubaxonium,^ n. gen. 



Definition. — C u b o s p h a3 r i d a with solid spongy spherical or octahedral shell, 

 without latticed medullary shell in the centre, and with six simple radial spines of 

 ec|ual size. 



The genus Cuhosplicera may be regarded as a form of Stypto.sphefra, which develops 

 six radial spines, opposite in pairs in the three dimensive axes. The solid spongy frame- 

 work of the shell assumes the outer form either of a sphere, or of a regular octahedron. 



1. Cubaxonium spongiosum, n. sp. 



Spongy shell spherical, composed of a very dense spongy framework of nearly uniform structure ; 

 the meshes three to four times as broad as the bars ; surface almost smooth. SLx spines cylin- 

 drical, twice to three times as long as the chameter of the spongy sphere, about as broad as 

 one half mesh. 



Dimensions. — Diameter of the sphere 0-2, meshes 0-006 to 0-008, bars 0-002 ; length of the 

 spines 0-4 to 0-5, breadth 0-004. 



Hahitat. — Soutli Pacific, Station 288, surface. 



2. Cubaxonium octahedrum, n. sp. 



Spongj' shell octahedral, composed of a loose spongy framework of nearly uniform structure ; 

 the meshes ten to twelve times as broad as the bars ; surface thorny. Six spuies three-sided 



^ Hexadorida = Ciibosphcerida spongiosa = Spongospha;rida hexacantha. 



2 (7M6axomM(»i = Shell with three axes like those of the cuhe ; xi/io;, i^irjwj. 



