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



3. Ellipsostylus psittacus, n. sp. (PI. 13, fig. 6). 



Proportion of the major axis to the minor = 4 : 3. Shell thin walled, with regular or subregular 

 rosette-shaped meshes, twice as broad as the bars ; eight to nine on the half equator ; each mesh 

 with three to four rounded lobes. Surface smooth. Polar spines sharp edged, very unequal; 

 longer spine about twice as long as the major axis, somewhat curved ; shorter spine scarcely longer 

 than the radius, shaped like a bird's head. 



Dimensions. Longer axis 0'08, shorter axis 0'06 ; pores O'Ol, bars O005 ; length of the polar 

 spines longer 015, shorter O'Oo. 



Habitat. Central area of the Pacific, Station 266, depth 2750 fathoms. 



4. Ellipsostijlus aquila, n. sp. (PI. 13, fig. 1). 



Proportion of the major axis to the minor = 7 : 6. Shell thick walled, with subregular, circular 

 meshes, five to six times as broad as the bars ; ten to twelve on the half equator. Surface smooth. 

 Polar spines sharp edged (six-sided ?), very unequal ; longer spine straight, about equal to the minor 

 axis ; shorter spine obliquely inserted, scarcely half as long, shaped like a bird's head. 



Dimensions. Longer axis 015, shorter axis 013; pores 0'02, bars 0'004; length of the polar 

 spines longer 01, shorter 0'05. 



Habitat. Central area of the Pacific, Station 272, depth 2600 fathoms. 



5. Ellipsostylus columba, n. sp. (PI. 13, fig. 3). 



Proportion of the major axis to the minor = 4: 3. Shell egg-shaped, thin walled, with regular, 

 circular meshes, three times as broad as the bars ; ten to twelve on the half equator. Surface 

 somewhat thorny. Polar spines nearly of equal length (equal to the major axis), but, of very 

 different form ; one straight, pyramidal, and obliquely inserted, the other like a bird's head. 



Dimensions. Longer axis 0'08, shorter 0'06 ; pores 0'003, bars O'Ol ; length of the spines 0'09. 



Habitat. South Atlantic, Station 332, surface. 



6. Ellipsostylus ciconia, n. sp. (PI. 13, fig. 8). 



Proportion of the major axis to the minor = 7:5. Shell egg-shaped, thick walled ; the meshes 

 very small, regular, circular, three times as broad as the bars; sixteen to twenty on the half equator. 

 Surface uneven. Polar spines nearly cylindrical, pointed ; the smaller obliquely inserted, equal to 

 the major axis ; the larger more than twice as long and thick, furrowed at its base. (Compare with 

 this and the allied species BhaMolithis pi-pa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, 



Taf. i. fig. 27.) 



Dimensions. Longer axis 0-07, shorter 0'05 ; pores 0'003, bars O'OOl ; length of the polar 



spines longer 0'2, shorter 0'08. 



Habitat. North Pacific, Station 253, depth 3125 fathoms. 



