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



4. Cijphonmm trtnacrium, n. sp. 



Cortical shell thick walled, with rough surface ; pores suhregular, circular (without hexa- 

 gonal frame), not broader than the bars ; five to six on the half meridian of each chamber, 

 nine to ten on its half equator. Medullary shells both compressed, lenticular. This species 

 resembles Cypassis entomocora vel Ommatocampe trinacria, Stohr, 1880, loc. cit., p. 90, Taf. ii. fig. 1, 

 but has not its external mantle. It may be the ancestral form of it (both in an ontogenetic and 

 phylogenetic sense). 



Dnnensions. — Main axis O'll, equatorial axis 0'07 ; greatest breadth 0'08 ; pores O'OOS, 

 bars 0-005. 



Hahitat. — Fossil in Tertiary rocks of Sicily, Caltanisetta, Haeckel (Grotte, Stohr ?). 



5. Cyphonium diattus, n. sp. 



Cortical shell thin walled, with quite smooth surface ; pores irregular, polygonal, mostly 

 pentagonal or hexagonal, three to six times as broad as the bars ; six to seven on the half 

 meridian of each chamber, ten to twelve on its half equator. IMedullary shells both spherical. 

 (Eesembles Ct/phonium profundmn, Ehrenberg, 1872, loc. cit, Taf. x. fig. 5, but does not possess 

 the spines of the surface.) 



Dimensions. — Main axis 0-13, equatorial axis 0'06 ; greatest breadth G'08 ; pores 0-005 to 0'012, 

 bars 0-002 to 0-00-4. 



Habitat. — Indian Ocean, western part (Zanzibar), Pullen, depth 2200 fathoms. 



6. Cijphonium mammarium, ii. sp. 



Cortical shell thick walled, with smooth surface (sometimes a little rough) ; pores iiTegular, 

 roundish, twice to three times as broad as the bars ; eleven to twelve on the half meridian of each 

 chamber, sixteen to nineteen on its half equator. Internal medullary shell spherical, external 

 lenticular compressed, sometimes both spherical or both compressed. (Eesembles the internal 

 cortical twin-shell of Cyphocolpus virginis, PI. 40, fig. 11.) 



BimensioTis. — Main axis 0-14, equatorial axis 0-08, greatest breadth 0-09 ; pores 0004 to 0-006, 

 bars 0-002. 



Habitat. — South Pacific, Station 285, depth 2375 fathoms. 



Subgenus 2. Ommatocyrtis, Haeckel. 

 Definition. — Surface of the cortical shell thorny or spiny. 



7. Cyphonium hexagonium, n. sp. 



Didymocyrtis hexagonia, Haeckel, 1881, Prodromus. 

 Cortical shell thin walled, with spiny surface ; pores regular or subregular, hexagonal, twice to 

 three times as broad as tlie bars ; five to six on the half meridian, nine to ten on the half equator 



