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



3. Conosphcera plagioconus, n. sp. (PI. 12, fig. 4). 



Pores of the shell irregular, polygonal, twice to five times as broad as the bars ; twenty to twenty- 

 four on the radius. Conical spines about eighty, irregularly formed and scattered, with oblique 

 (not radial) axes ; about as high as broad, with eight to twelve pores in the wall. 



Dimensions. Diameter of the shell 0'25, pores - 005 to 0'015, bars O003 ; length of the spines 

 0-02, basal breadth 0'02. 



Habitat. Central Pacific, Station 265, depth 2900 fathoms. 



Genus 91. Coscinomma, 1 n. sp. 



Definition. A strosphserida with one simple lattice -sphere, covered with 

 simple radial spines ; the pores between them prolonged into hollow, conical, or 

 cylindrical tubuli. 



The genus Coscinomma exhibits among the Astrosphserida the same peculiar 

 formation that distinguishes Ethmosphcera and Sethosphcera among the Liosphserida ; 

 each pore of the simple shell is prolonged into a short conical or cylindrical tubulus, 

 as a rule either on the outside or on the inside of the shell, but sometimes on both sides. 



Subgenus 1. Coscinommarium, Haeckel. 



Definition. Pores prolonged into short tubes both on the inside as well as the out- 

 side of the. shell. 



1. Coscinomma amphisiphon, Haeckel (PI. 26, figs. 1, la, 1&). 



Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the inside as 

 well as on the outside of the shell into a short truncated conical tube ; fifteen to eighteen pores on 

 the radius. In each hexagon-corner arises a bristle-shaped radial spine, half as long as the 

 radius. 



Dimensions. Diameter of the shell 0'22, pores O'Ol, bars 0'005 ; length of the spines 01. 



Habitat. Central Pacific, Station 271, surface. 



Subgenus 2. Coscinommidium, Haeckel. 

 Definition. Pores prolonged into external tubes on the outside of the shell. 



2. Coscinomma ectosiphon, n. sp. 



Pores regular, circular, hexagonally framed, twice as broad as the bars, prolonged on the outside of 

 the shell into a short truncated conical tube; ten to twelve pores on the radius. In each hexaon- 



1 Coscinomma = Sieve eye ; KOUXWOU, 



