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



12. ThecosphcBra dodecactis, n. sp. 



Cortical shell thin walled, smooth, with large irregular roundish pores, two to eight times as 

 broad as the bars. Both medullary shells with regular circular pores, twice as broad as the bars. 

 Radial proportion of the three splieres = 1:2:5; they are connected by twelve regularly disposed 

 stout radial beams. 



Dimensions.— DiixmeieT: of the outer shell 0"2, middle 0-08, inner 0"04 ; cortical pores 0'004 

 to 0-016, bars 0-002. 



Habitat. — Central Pacific, Station 263, depth 2650 fathoms. 



13. TJiecosphcera icosactis, n. sp. 



Cortical shell tliin walled, with small irregular roundish pores, two to four times as broad as 

 the bars. Both medullary shells with similar but smaller pores. Eadial proportion of the 

 three spheres = 1:3:8; they are connected by twenty thin radial beams. 



Dimensions. — Diameter of the outer shell 0"32, middle 0-12, inner 0-04 ; cortical pores 0-005 

 to 0-012, bars 0-003. 



Habitat. — North Pacific, Station 244, depth 2900 fathoms. 



14. Tliecospha'ra maxima, u. sj). 



Cortical shell thin walled, with small irregular roundish pores, two to six times as broad as 

 the bars. Both medullary shells with similar, but smaller, pores. Eadial proportion of the three 

 spheres = 1:3:9; they are connected by numerous (forty to sixty or more) thin radial beams. 



Dimensions. — Diameter of the outer shell 0-45, middle 0-15, inner 0-05 ; cortical pores 0-008 

 to 0-024, bars 0-004. 



Habitat. — Central Pacific, Station 272, depth 2600 fathoms. 



Genus 22. Rhodosphcera,^ Haeckel, 1881, Prodromus, p. 452. 



Definition. — L i o s p h te r i d a with one medullary (intracapsular) shell and two 

 cortical (extracapsular) shells. 



The genus Rhodosphcera differs from the preceding ThecosphcBra in the same 

 manner in which, among the Dyosphserida, LiosphcBra differs from Carposphcera. The 

 cortical shell is double, composed of two not far distant shells, lying outside the central 

 capsule. The distance between the shells is much smaller than the radius of the inner 

 shell. This is connected by radial beams (piercing the central capsule) with the small 

 central medullary shell. 



Subgenus 1. RhodosphcBrella, Haeckel. 



Definition. — Pores of both cortical shells regular, in each shell all of nearly equal size 

 and form. 



J i?/iodos2}/icEra = Eose-spliere ; foiua, a^u'ii^a,. 



