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



Dimensions. Length of the shell (without spines) 0'13, breadth O'l, thickness 0'07 ; pores and 

 bars 0-004 to OD06. 



Habitat. Pacific, central area, Station 273, surface. 



Subfamily 2. COCCOLARCIDA, Haeckel. 



Definition. L arcarida with encased lentelliptical shell, composed of two or 

 more concentric lentelliptical latticed shells, which are united by radial beams (at 

 least one inner medullary shell and one outer cortical shell). 



Genus 268. Coccolarcus, 1 n. gen. 



Definition.-' L arcarida with two concentric latticed shells, an outer lentelliptical 

 cortical shell, and an inner (spherical or lentelliptical) medullary shell, both connected 

 by radial beams. Surface without radial spines. 



The genus Coccolarcus differs from Cenolarcus by the possession of an internal 

 medullary shell. This is quite simple, either spherical or lentelliptical, and connected 

 with the outer cortical shell by a number of radial beams. In the similar Larnacilla 

 this connection is effected by four internal latticed lamellae (the half lateral wings of 

 the transverse girdle) ; therefore we find here four internal gates (on the poles of the 

 principal axis), absent in Coccolarcus. 



1. Coccolarcus lentellipsis, n. sp. 



Cortical shell with smooth surface and regular network ; pores circular, twice as broad as 

 the bars ; about thirteen on the half meridian, eleven on the half equator. Proportion of the three 

 dimensive axes = 3:4:5. Medullary shell spherical, half as broad as the transverse radius. 



Dimensions. Principal axis (or length) of the cortical shell 0'15, transverse axis (or breadth) 

 012, sagittal axis (or thickness) 0'09 ; pores O'Ol, bars 0'005 ; diameter of the medullary shell 

 0-03. 



Habitat. Pacific, central area, Station 272, depth 2600 fathoms. 



2. Coccolarcus platellipsis, n. sp. 



Cortical shell with thorny surface and irregular network ; pores roundish, twice to three 

 tunes as broad as the bars ; sixteen to eighteen on the half meridian, ten to twelve on the half 

 equator. Proportion of the three dimensive axes = 1:2:3. Medullary shell lentelliptical, one- 

 third as large as the cortical shell. 



1 Coccolarcus = Basket with kernel; xdxxo;, Axo;. 



