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



Dimensions. — Diameter of the outer shell 0'42, inner 0'4, distance of both O'Ol ; diameter 

 of the meshes 0-02 to 0-06. 



Habitat. — North Pacific, Station 250, surface. 



5. Liosphcera polypora, n. sp. (PI. 20, fig. 2). 



Both shells with small ii-regular rounchsh pores, of about the same size as the bars between 

 them ; twenty to thirty on the quadrant. The pores of the outer shell somewhat smaller, there- 

 fore much more numerous than the pores of the inner shell. Distance between the two shells about 

 one-tliird as great as the radius of the inner. Both shells connected by numerous thin radial beams. 

 Surface smooth or a Uttle rough. 



Diinensions. — Diameter of the outer shell 0'18, inner 0'14, distance of both 0'02 ; pores and 

 bars 0003 to 0005. 



Habitat. — West Tropical Pacific, Station 225, depth 4475. 



Subfamily Thecosph^rida,^ Haeckel, 1881, Prodromus, pp. 449, 452. 



Definition. — L iospliserida with three concentric spherical lattice-shells, which are 

 united by radial beams. 



Genus 21. TliecosplKBra,'' Haeckel, 1881, Prodromus, p. 452. 



Definition.- — L iosphserida T\dth two medullary (intracapsular) shells and one 

 cortical (extracapsular) shell. 



The genus TJiecosphcera comprises a large number of triple-shelled S p h 33 r o i d e a, 

 formerly united with Actinomma, but different from this genus in the absence of 

 radial spines. The latticed shell is composed of three concentric spheres, two of which 

 lie within the central capsule (medullary shells), and one outside (cortical shell). This 

 latter is connected with the former by radial beams piercing the wall of the central 

 capsule. From the following Rliodosphcera (mth one medullary and two cortical 

 shells) Cai'posphcera differs also by the distance of the three shells. In the former 

 the distance between the two outer shells is much smaller, in the latter much larger, 

 than the distance between the inner shells. 



Subgenus 1. ThecosphcBrantha, Haeckel, 



Definition. — Pores of the cortical shell regular, hexagonal, or circular, with hexagonal 

 frames or lobes, all of nearly equal size and form. 



^ Thecospliserida = Liosplia;rida triplicia=Triosph8erida anacantha. 

 2 r/iecos^7ia:ra=Capsule-spliere ; 6-ijx.n, a$ai^a. 



