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



Subfamily CLATHEOSPHJERIDA, Haeckel, 1881, Prodromus, p. 472. 



Definition. C ollosphserida with a double lattice-shell around every central 

 capsule of the ccenobium ; both concentric shells connected by irregular or subradial 

 beams, commonly solid or lamellar staffs, rarely hollow tubes. 



Genus 43. Clathrosphcera, 1 Haeckel, 1881, Prodromus, p. 472. 



Definition. C ollosphserida with a double lattice-shell around every central 

 capsule of the ccenobium ; surface of the outer shell smooth. 



The genus Clathrosphcera (with smooth svirface) and the following Xanthiosphcera 

 (with spiny surface) form together the small subfamily, Clathrosphserida, different 

 from the other Collosphserida by the double lattice-shell. From the surface of the inner 

 primary shell arise either solid spines or hollow tubes, which unite by the anastomosis 

 of irregular branches and so form the outer secondary shell, often very incomplete 

 and irregular. All Clathrosphaerida seem to inhabit great depths. 



Subgenus 1. Clathrosphcerula, Haeckel. 



Definition. The connecting staffs between both shells are hollow tubes (derived 

 from Siphonosphcera). 



1. Clathrosphcera circumtexta, n. sp. (PI. 8, fig. 6). 



Inner shell spherical, with irregular roundish large meshes, now broader now smaller than their 

 bars. Eight to ten meshes in the half meridian of the shell. All these meshes are prolonged into 

 short cylindrical hollow tubes, about as long as broad, somewhat constricted in the middle. From 

 the margins of the outer openings of these tubes proceed very numerous and delicate siliceous 

 filaments, which all lie on the same spherical face, branch, anastomose, and twine over the openings 

 and the intervals between them, forming a very thin, arachnoid spherical outer shell. The meshes 

 of this are quite irregular polygonal, of very different size and form. The radius of the inner 

 shell bears to that of the outer a ratio = 5:6. 



Dimensions. Diameter of the inner shell Oil to 013, of the outer 013 to 016 ; meshes of 

 the inner shell 0'005 to 0'02, of the outer O'OOS to 0'04. 



Habitat. North Pacific, Stations 238 to 253, depths 2050 to 3950 fathoms. 



Subgenus 2. Clathrosphcerium, Haeckel. 



Definition. The connecting staffs between the two shells are solid rods or lamellar 

 spines (derived from Acrosphcera). 



1 Clathrosphtera Lattice-sphere. 



