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



1. Spongotrodius hrevispinus, Haeckel. 



Spongotrochus hrevispinus, Haeckel, 1862, Monogr. d. Eadiol., p. 402, Taf. xxvii. figs. 4, 5. 



Spongy framework of the whole disk irregular, everywhere equal. The whole surface of the 

 disk covered with numerous short, needle-shaped, radial spines, about as long as the thickness of 

 the disk, which is one-fifth of its diameter. 



Dimensions. — Diameter of the disk 0-18 ; length of the radial spines 0-03 to 0'04, basal breadth 

 0-002. 



Habitat. — Cosmopohtau ; Mediterranean, Atlantic, Pacific, surface. 



2. Spongotrochus muUispinus, n. sp. 



Spongy framework of the whole disk irregular, in the centre darker. The whole surface of the 

 disk covered with numerous conical radial spines, about as long as the radius of the disk. 



Dimensions.- — Diameter of the disk 0-22 ; length of the raihal spines 01, basal breadth 0-008. 

 Habitat. — Pacific, central area. Stations 271 to 274, surface. 



3. Spongotrochus longispinus, Haeckel. 



Sp>onrjoiroclms longispinus, Haeckel, 1862^ Monogr. d. Radiol., p. 463, Taf. xxvii. figs. 2, 3. 



Spongy framework of the whole disk irregular, everywhere equal. Surface thorny. Twenty 

 long, needle-shaped, radial spines, about as long as the diameter of the disk, synometrically 

 distributed in pairs on both flat sides of the disk, so that the opposite pairs lie in five equidistant, 

 meridian planes (compare the figures). 



Dimensions. — -Diameter of the disk 0-2 ; length of the twenty radial spines 0-2, basal breadth 0-001. 



Habitat. — Mediterranean (Messina), surface. 



Subgenus 2. Stylospongidium, Haeckel, 1881, Prodromus, p. 460. 



Definition. — Spongy framework of the disk in the inner part with concentric rings 

 or spiral convolutions, in the outer part quite irregular. 



4. Spongotrochus scutella, n. sp. 



Spongy framework of the disk in the inner part with four to six concentric rings, in the outer 

 part quite irregular. The whole surface of the disk covered with bristle-shaped radial spines, about 

 lialf as long as the radius of the disk. 



Dimensions. — Diameter of the disk 0-24 ; length of the radial spines O'OG, basal breadth 0-02. 



Habitat. — Antarctic Ocean, Station 157, depth 1950 fathoms. 



