1608 THE VOYAGE OF H.M.S. CHALLENGER. 



5. Sagosphcera coronilla, n. sp. 



Eadial spines slender, smooth, three to six arising from each nodal point of the network in 

 . divergent directions, about as long as its smooth bars, crowned at the distal end with a bunch of 

 twenty to thirty radial terminal branches, and provided with a spinulate knob at the distal end 

 (similar to Sagcnosccna stcllata, PL 108, iig. 3). 



Dimensions. — Diameter of the sphere S'O, length of the bars 01 to 0-2, breadth 0002. 

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



Genus 677. Sagoscena,^ n. gen. 



Definitioti. — S agospliasricla with a delicate s]3herical shell, the thin wall of 

 which is composed of a simple lattice-plate and covered with numerous pyramidal 

 elevations ; each pyramid bears on its top one or more radial spines, but has no axial 

 rod in its radial axis. 



The genus Sagoscena, and the following closely allied Sagenoscena (l)oth very 

 common and widely distributed), exhibit a peculiar and very remarkable structure of 

 the delicate lattice-shell, similar to that which Auloscena represents among the Aulo- 

 sphserida. The surface of the simple spherical lattice-shell is covered with numerous 

 pyramidal or tent-shaped elevations. These elegant and delicate pyramids are, how- 

 ever, in Sagoscena usually not so regular as in the similar Auloscena ; the edges of 

 the pyramids are in the latter hollow cylindrical tubes, in the former thin solid 

 threads. The top of each pyramid usually bears a bunch of apical sj)ines. 



1. Sagoscena castra, n. sp. (PI. 108, fig. l). 



Pyramids subregular, of equal size and similar form, usually three-sided, crowned at the top 

 with three divergent apical spines, which alternate with the three edges of the pyramids and bear 

 a small spinulate terminal knob. (Some four-sided and single five-sided pyramids are often inter- 

 mingled with the three-sided.) 



Dimensions. — Diameter of the sphere 17 to 2'3, length of the bars 0'2 to 0'25, breadth 0*008. 



Habitat. — South-Eastern Pacific, Stations 295, 296, surface. 



2. Sagoscena tentorium, n. sp. (PI. 108, fig. 6). 



Pyramids subregular, of equal size and similar form, usually four-sided, crowned at the top 

 with three divergent apical spines, which are trifurcate at the distal end. (Some three-sided and 

 five-sided pyramids are often intermingled with the four-sided.) 



Dimensions. — Diameter of the sphere 2-2, length of the bars 0-2 to 0-25, breadth 0-005. 



Haiitat. — South Pacific, Station 291, surface. 



' iSaposcena= Armour with tents ; (!X'/r,,uy.r,uvi. 



