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



Dimensions. Main axis (without spines) 012, greatest breadth 0'08 ; pores O005 to.0'001, 

 bars 0-002 ; length of the polar spines 0'02 to 0'06, basal thickness O'Ol. 



Habitat. Northern Pacific, Californian Sea, depth 2500 fathoms, Ehrenberg ; Station 253, depth 

 3125 fathoms. 



Subgenus 2. Cyphinidura, Haeckel. 

 Definition. On both poles of the cortical shell, a circle of divergent polar spines. 



3. Cyphinidium coronatum, n. sp. 



Cortical shell with thorny surface, and irregular, roundish pores, twice to four times as broad as 

 the bars ; seven to eight on the half meridian, eleven to thirteen on the half equator of each 

 chamber. Around both poles of the main axis occurs a circle of ten to twelve strong, radially 

 divergent spines, about as long as the diameter of the outer medullary shell, which, like the inner, is 

 spheroidal. (This species is identical with the younger developmental stage of Panidum coronatum, 

 PI. 40, fig. 4, before the formation of two distal chambers.) 



Dimensions. Main axis 012, greatest breadth 01 ; pores O'OOS to 0'016, bars 0'004 ; length of 

 the polar spines 0'02, thickness 0'005. 



Habitat. Pacific, central area, Stations 270 to 274, depth 2350 to 2925 fathoms. 



Genus 161. Cannartiscus, 1 n. gen. 



Definition. Cyphinida with simple cortical shell and simple medullary shell, 

 with two hollow fenestrated polar tubes, opposite on both poles of the main axis. 



" The genus Cannartiscus differs from Cyphanta in the development of two hollow 

 fenestrated tubes, opposite on both poles of the main axis. It simulates therefore the 

 characteristic formation of Cannartus, and differs from this Artiscid in the possession of 

 a medullary shell. 



1. Cannartiscus amphiconiscus, n. sp. (PL 39, fig. 19). 



Cannartidmm amphiconiscus, Haeckel, 1882, Atlas (pi. xxxix. fig. 19). 



Cortical shell thick walled, smooth, with regular, circular pores, twice as broad as the bars ; 

 nine to ten on the half meridian, sixteen to eighteen on the half equator of each chamber. Polar 

 tubes conical, about as long as one single chamber, on the base somewhat broader than the simple 

 spherical medullary shell. Pores of the tubes only one-third as great as those of the chambers. 



Dimensions. Main axis of the cortical shell (without tubes) 014, greatest breadth 0'1 : 

 1 GannartisciM = Small loaf with tubes ; xiiyyct, ajr/Vxe/f. 



