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



Dimensions. Diameter of the shell 0'09 to Oil, of the pores 0'002 to 0'004, of the bars 

 0-003 to 0-006 ; length of the tubuli 0'05 to 0'06 ; diameter of the inner aperture 0'02 to. 0'03, of 

 the outer aperture 0'05 to 0'07. 



Habitat. Western part of the South Atlantic, Station 325, surface. 



Genus 41. Otosphcera, 1 n. gen. 



Definition. Collosph ser i da with simple shells, the pores of which are pro- 

 longed into external simple radial tubuli with fenestrated walls ; outer mouth of the 

 tubuli armed with a single tooth. 



The genus Otosphcera differs from Solenosphcera by the single tooth on the external 

 mouth of the tubuli, from Mazosphcera by the fenestration of the walls of the tubuli. 



1. Otosphcera polymorpha, n. sp. (PI. 7, fig. 6). 



Shell quite irregular, polyhedral or roundish, very variable in size and form, with numerous very 

 small pores, much smaller than the bars. Twenty to thirty pores in the half meridian of the shell. 

 Porous tubuli of the shell commonly in variable number (one to four), but sometimes constant in 

 number (one, two, three, or four) in the one and same colony. Tubuli irregular conical, 

 commonly about as long as the radius of the shell ; their outer aperture obliquely truncated, on one 

 side prolonged into one large, prominent, bill-like, curved, acute tooth. 



Dimensions. Diameter of the shell 012 to 015, of the pores O'OOl to 0'002 ; length of the 

 tubuli 0'06 to - 08, inner aperture - 03, outer aperture 0'02. 



Habitat. Indian Ocean, Madagascar, Eabbe, surface. 



2. Otosphcera auriculata, n. sp. (PL 7, fig. 5). 



Shell quite irregular, of extremely variable form, now inclining to roundish, now to polyhedral, 

 with very numerous small pores, irregularly formed and distributed. Twelve to twenty-four pores 

 in the half meridian of the shell, of very different size, for the most part larger than the bars. Porous 

 tubuli of the shell of variable number (in one and the same colony), one to five, mostly three or 

 four, of conical form, irregularly formed and scattered, commonly about half as long as the radius 

 of the shell. Outer aperture of the tubuli obliquely truncated, with one large prominent, often 

 curved, acute tooth. 



Dimensions. Diameter of the shell 01 to 0'2, of the pores 0'003 to 0'005 ; length of the tubuli 

 O'Ol to 0'05, inner aperture 0~04, outer aperture 0'03. 



Habitat. Central Tropical Pacific, Stations 268 to 272, depths 2425 to 2925 fathoms. 



1 Otosphcera - Shell with ears ; 



