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



Genus 257. Spongostaurus^ Haeckel, 1881, Prodromus, p. 461. 



Definition. S pongodiscida with four solid radial spines on the margin of the 

 circular or square disk, commonly crossed in two equatorial diameters perpendicular one 

 to another. 



The genus Staurodictya exhibits four marginal spines in cross form. Commonly 

 the cross is regular and rectangular, the four spines being opposite in pairs in two 

 perpendicular diameters; sometimes more or less irregular. The genus repeats 

 Staurodictya among the Porodiscida, Staurocyclia among the Coccodiscida. 



1. Spongostaurus cruciatus, n. sp. 



Spongy disk circular ; four radial spines on its margin opposite in two crossed equatorial 

 diameters, perpendicular one to another, conical, about as long as the diameter of the disk. 

 Dimensions. Diameter of the disk 0'16 ; length of the spines 0'18, basal breadth 0'04. 

 Habitat. North Pacific, Station 244, depth 2900 fathoms. 



2. Spongostaurus serratus, n. sp. 



Spongy disk circular ; four crossed radial spines very large, twice to three times as long as the 

 diameter of the central disk, serrated on both edges, with two rows of strong conical perpendicular 

 teeth (similar to the saw of Pristis antiquorum). 



Dimensions. Diameter of the disk 01 ; length of the spines 0'2 to 0'3, breadth 0'02. 



Habitat. Indian Ocean, Madagascar, Eabbe, surface. 



3. Spongostaurus hastatus, n. sp. 



Spongy disk square, with concave sides; four crossed radial spines cylindrical, on the broader 

 distal end spear-shaped or nearly lanceolate, one and a half times as long as the diameter of the 

 disk. 



Dimensions. Diameter of the disk 013 ; length of the spines 0'2, basal breadtli O'Ol, distal 

 breadth 0'03. 



Habitat. Tropical Atlantic, Station 347, surface. 



4. Spongostaurus quadratus, n. sp. 



Spongy disk square, with rectilinear sides ; four crossed radial spines pyramidal, arising from 

 the corners of the square, about as long as its half diagonal. 



Dimensions. Diameter of the disk 016 ; length of the spines O'OS, basal breadth 0'02. 

 Habitat. Pacific, central area, Station 271, surface. 



1 Spongostaurus = Spongy disk with crossed spines ; axoyyo;, 



