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



1. Odontosphcera monodon, n. sp. (PI. 5, fig. 5). 



Shell spherical or subspherical, with very small and numerous circular pores, much smaller 

 than the bars. Twelve to fifteen pares on the half meridian of the shell. Between them a 

 variable number of larger roundish apertures (mostly twelve to sixteen) irregularly scattered, one- 

 fourth to one-fifth as broad as the shell radius. On the margin of every larger aperture a single 

 (rarely two or three) sharp conical tooth, about as long as the diameter of the aperture, and obliquely 

 laid over them. 



Dimensions. Diameter of the shell 01 to 013, of the pores O'OOl to 0'003, of the bars O'Ol to 

 0'02, of the larger apertures O'Ol to 0'02. 



Habitat. Sunda Archipelago, Station 192, surface. 



2. Odontosphcera cyrtodon, n. sp. (PI. 5, fig. 6). 



Shell spherical or subspherical, with numerous roundish pores of very irregular size and 

 distribution, mostly larger than the bars. Ten to twelve pores on the half meridian of the 

 shell Between them a variable number (mostly six to nine) of large roundish pores, about half as 

 broad as the shell radius, armed on one side of the margin with one single large tooth, about as 

 long as the diameter of the aperture, hook-like, curved, and obliquely laid over them. 



Dimensions. Diameter of the shell 012 to 014, of the pores O'Ol to 0'02, of the bars O'OOS to 

 0-006, of the larger apertures 0'03 to 0'04. 



Habitat. Indian Ocean, near the Cocos Islands, Babbe, surface. 



Genus 35. Choenicosphcera, 1 n. gen. 



Definition* C ollosphaerida with simple shells, armed on the outside with 

 radial spines, forming elegant coronals around the larger pores. 



The genus ChcenicospJicera is characterised by the peculiar disposition of its radial 

 spines, which form protective coronals around the larger pores, or even around all pores 

 of the shell. 



Subgenus 1. Chcenicosphcerula. 

 Definition. A coronal of spines around every pore of the shell. 



1. Chcenicosphcera murrayana, n. sp. (PI. 8, fig. 4). 



Shell spherical, with large circular or roundish pores of unequal size, two to four times as 



broad as the bars. Ten to twelve pores in the half meridian of the shell. Margin of every pore 



1 Clia;nicospha:ra = Shell with coronel trepans ; xomlxvi 



