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



11. Cyphonium ceratospyris, Haeckel. 



Didymocyrtis ceratospyris, Haeckel, 1862, Monogr. d. Radiol., p. 445, pi. xxii. figs. 14-16. 

 Haliomina didymocyrtis, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 816. 



Cortical shell thin walled, with spiny surface ; pores irregular, roundish, three to nine times 

 as broad as the bars ; five to six on the half meridian of each chamber, eight to nine on its 

 half equator. Spines of the surface partly very short, partly as long as the largest pores, either 

 radially or obliquely inserted. Medullary shells both spherical. (Compare the detailed description 

 and figures also of the soft body in my Monograph, Joe. cit.) 



Dimensions. Main axis of the cortical shell 0'12, equatorial axis (in the stricture) 0'06 ; 

 greatest breadth 0'08 ; pores 0'03 to 0'2, bars 0'002 to O006, spines 0'05 to O'OIS. 



Habitat. Mediterranean (Messina), Canary Islands (Lauzerote), Haeckel. 



Genus 157. Cypassis, 1 n. gen. 



Definition.- C yphinida with double cortical shell and double medullary shell, 

 without polar spines or tubes. 



The genus Cypassis differs from Cyphonium by duplication of the cortical twin-shell; 

 from the outer surface of the simple twin-shell arise numerous radial spines, which become 

 connected by anastomosing transverse branches, and in this manner form an outer 

 envelope or mantle. Cypassis may also be regarded as a Cromyodruppa, the double 

 cortical shell of which is constricted in the equatorial plane. 



Subgenus 1. Didymospyris, Haeckel (1881). 

 Definition. -Surface of the shell smooth, without thorns or spiinvs. 



1. Cypassis palliata, n. sp. 



Inner cortical shell thin walled, with regular, circular, hexagoaaUy-framed pores, twice as broad 

 as the bars ; seven to eight on the half meridian of each chamber, ten to twelve on its half equator. 

 Outer cortical shell very thin, with smooth surface, and very small, irregular, roundish pores, twice 

 to five times smaller than those of the inner shell. Distance between the two cortical shells 

 equals the diameter of the outer medullary shell, which, like the inner, is spherical. (The net- 

 work of this species resembles that of Peripanartus amjikiconisciis, I'l. 40, fig. 5.) 



Dimensions. Main axis of the external cortical shell O18, of the internal 012 ; greatest 

 breadth (in the equator of each chamber) of the former 0'13, of the latter 0'09 ; pores of the outer 

 0-002 to 0-005, of the inner shell O'Ol, bars 0'002 to <H)0.~>. 



Habitat. South Pacific, Station 288, surface. 



1 Cypassis = wxaaai; ; A girl's girdK-. 



