1614 THE VOYAGE OF H.M.S. CHALLENGER. 



composed of four crossed small branches with a spinulate terminal knob. Bars of the spongy 

 framework partly covered with similar verticils. 



Dimensions. Diameter of the sphere 2'0 to 3'0, length of the bars 0'2 to 0'3, breadth O002 

 to 0-003. 



Habitat. North Pacific, Stations 240 to 244, surface. 



4. Sagmidium quadricorne, n. sp. (PI. 108, fig. 12). 



Eadial spines stout, smooth, cylindrical, usually four divergent arising from each nodal point of 

 the surface (sometimes three, five, or six, instead of four). Each spine bears on its distal end a 

 club-shaped stellate knob. Bars of the spongy framework smooth. 



Dimensions. Diameter of the sphere 4'5, length of the bars 0'2 to 0'3, breadth 0'003 to 0'005. 



Habitat. South Pacific, Station 293, depth 2025 fathoms. 



5. Sagmidium multicorne, n. sp. 



Kadial spines slender, more or less curved, verticillate, in variable number (three to six) 

 divergent, arising from the nodal points of the surface. The spines as well as the bars of the 

 spongy framework are partly simple, partly covered with irregularly scattered cruciate verticils, very 

 similar to those of Sagmarium trigonizon (or Dictyosoma trigonizon), figured in my Monograph, 

 pi. xxvi. figs. 4, 5. 



Dimensions. Diameter of the sphere 5'0, length of the bars 0'2 to 0'3, breadth - 003. 



Habitat. Indian Ocean, Cocos Islands (Rabbe), surface. 



Genus 681. Sagoplegma, 1 n. gen. 



Definition. S agosphserida with a spongy spherical shell, the thickened wall of 

 which is composed of a loose spongy framework, and bears on its surface numerous 

 pyramidal elevations. 



The genus Sagoplegma differs from Sagmarium, its ancestral form, in the development 

 of pyramidal or tent-shaped elevations on the surface of the spongy hollow sphere. It 

 exhibits, therefore, the same relation to the latter as the similar Sagoscena bears to 

 Sagena. The wall of the spherical shell is in the two latter genera a thin simple lattice- 

 plate, in the former a thickened spongy framework. 



1. Sagoplegma pyramidophora, n. sp. 



Pyramids on the surface of the spongy sphere subregular, mostly tetrahedral, of nearly equal 

 size and similar form. The three edges of each pyramid are prolonged over its top into three 



1 Sagoplegma = Armour of framework ; acc'/n, 



