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



send out lateral branches. All these branches lie on a spherical face, and form by communications 

 the irregular delicate network of the outer shell, very like that of the inner, with large polygonal 

 meshes, six to eight meshes in the half meridian of the shell. Surface of the outer shell covered 

 with numerous straight spines, prolongations of the inner spmes, but only half as long as these. 

 The radius of the inner shell bears to that of the outer a ratio = 3:5. 



Dimensions. — Diameter of the inner shell 01 to 0'12, of the outer Olo to 019; pores of the 

 inner shell 0-02 to O'Ol to O'OG, of the outer 0-04 to 0-06 to 0-08 ; length of the outer spines 

 001 to 002. 



Habitat — Central area of the Tropical Pacific, Station 263, depth 2650 fathoms. 



2. XanthiosphcBra erinacea, n. sp. (PI. 8, fig. 9). 



Inner shell spherical, with irregular roundish meshes, one-half to two times as broad as the 

 bars. Fifteen to twenty meshes in the half meridian of the shell. From its surface arise numerous 

 thin radial spines, which at equal distances from the surface send out lateral branches. All these 

 branches lie on the face of a sphere, and form by communications the irregular delicate network of the 

 outer shell, very unlike that of the inner, with large polygonal meshes, twelve to twenty-four in the 

 lialf meridian of the shell. Surface of the outer shell covered with numerous straight spines, pro- 

 longations of the inner spines, and of the same length. The radius of the inner shell bears to 

 that of the outer a ratio = 3:4. 



Dimensions. — Diameter of the inner shell 01 to 012, of the outer 013 to 016 ; pores of the 

 inner shell 0-002 to 0-008, of the outer 0-01 to 0-03 ; length of the outer spines 0-02 to 0-03. 



EaUtat. — Central area of tlie Tropical Pacific, Stations 270, 272, depth 2925 and 2600 fathoms 

 respectively. 



3. XanthiosphcBra lappacea, n. sp. (PI. 8, fiigs. 10, 11). 



Inner shell spherical or subspherical, with very small roundish pores, quite irregularly scattered, 

 one-fourth to three-fourth as broad as their bars. Ten to twenty pores in the half meridian of the 

 shell. From its surface arise in an extremely irregular and variable manner numerous oblique spines, 

 often curved, often lamellar, and perforated by pores, sometimes hollow, fenestrated cones. At 

 different distances from the surface these spines send out lateral curved branches, which by communi- 

 cations form the delicate and very irregular network of the outer shell. This network is often 

 incomplete and very unlike that of the inner shell, with large polygonal meshes, six to eighteen in 

 the half meridian of the shell. Surface of the outer shell covered with umnerous small, curved, and 

 oblique spines, prolongations of the inner spines, but scarcely one-third to one-half as long as these. 

 The radius of the inner shell bears to that of the outer a ratio = 3:4. 



Dimensions. — Diameter of the inner shell 0'08 to 0-12, of the outer Oil to 0-15 ; pores 

 of the inner shell O'OOl to 0-009, of the outer O'Ol to 0-04; length of the outer spines O'OO.t 

 to 0009. 



Habitat. — Central area of the Tropical Pacific, Stations 263 to 274, depths 2350 to 3000 fathoms. 



