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



Dimensions. Main axis of the cortical shell O'll, equatorial axis 0'06 ; meshes O'Ol to 002, bars 

 0-002 ; diameter of the medullary shell 0'02. 



Habitat. Atlantic, Canary Islands (Lanzerote), surface. 



Subgenus 2. Cyphantissa, Haeckel. 



Definition. Surface of the cortical shell spiny, everywhere scattered with numerous 

 thorns or spines. 



5. Cyphanta hispida, n. sp. 



Cortical shell thick walled, with spiny surface ; pores regular, circular, with hexagonal frame, 

 twice as broad as the bars ; twelve to fourteen on the half meridian, eight to ten on the half 

 equator. From the corners of the hexagonal frames (between every three pores) arise short, straight, 

 conical radial spines, somewhat longer than the breadth of the pores. Medullary shell subspherical, 

 its diameter about one-third of the equatorial axis of the cortical shell. (The appearance of the 

 cortical shell is the same as that of the middle part of Peripanartus amphiconus, PI. 40, fig. 5.) 



Dimensions. Main axis of the cortical shell 0'12, equatorial axis 0'07 ; meshes O'Ol, bars 0'005 ; 

 length of the spines 0'012 ; diameter of the medullary shell - 02. 



Habitat. Pacific, central area, Station 274, depth 2750 fathoms. 



6. Cyphanta hystrix, n. sp. 



Cortical shell thin walled, with thorny surface ; pores irregular, roundish, of very unequal 

 size, twice to six times as broad as the bars ; twelve to eighteen on the half meridian, eight to 

 thirteen on the half equator. Between the pores irregularly scattered, bristle-like, thin spines 

 about the same size, partly straight, partly oblique, rising from the surface. Medullary shell 

 lenticular, compressed, its equatorial axis one and a half times the length of the main axis, and 

 about half that of the cortical shell. 



Dimensions. Main axis of the cortical shell 0'15, equatorial axis 0'09 ; meshes 0'004 to - 02, 

 bars 0-003 to 0'006 ; length of the spines 0'02 ; diameter of the medullary shell 0-04. 



Habitat. South Atlantic, Station 318, surface. 



Genus 156. Cyphonium, 1 n. gen. 



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

 without polar spines or tubes. 



The genus Cyphonium contains a number of very common species, among which are 

 the earliest known forms of this family, partly described by Ehrenberg as Ommatospyru 



1 Cyphonium, Roundish vessel ; x 



