460 THE VOYAGE OF H.M.S. CHALLENC4ER. 



3. Lithocyclia ocellus, Ehrenberg. 



Lithoci/dia ocelliis, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. tig. 30; Ahhandl. d. k. Akad. d. 

 Wiss. Berlin, 1875, Taf. xxix. fig. 3. 



Phacoid shell three times as broad as the medullary shell, surrounded by numerous (seven to 

 eleven) chambered rings, which are divided by piercing radial beams each into sixty to ninety 

 claambers. Margin of the disk smooth. Pores regular, circular ; nine on the radius of the phacoid 

 sliell, one single pore on each chamber. 



Di?nensions. — Diameter of the disk (with eleven rings) 0'22, of the phacoid shell O'l, of the 

 medullary shell 0-035. 



Habitat. — Fossil in the rocks of Barbados. 



4. Lithocyclia monococcus, ii. sp. 



Stephanopyxis (Jtibiosa {fj, Bury, 1862, Polycystins of Barbados, pi. xiii. tigs. 1, 2. 



Phacoid shell four tunes as broad as the medullary shell, suri'ounded by numerous (five to 

 eight) chambered rings, which are divided by piercing radial beams each into fifty to seventy 

 cliambers. Margin of the disk thickened, thorny. Pores regular, circular ; seven on the radius 

 r)f the phacoid shell, one single pore on each cliamber. 



Bimcnsiom. — Diameter of the disk (witli eiglit rings) CIS, of the phacoid shell 0-12, of the 

 medullary shell 0'03. 



Habitat. — Pacific, central area. Station 267, depth 2700 fathoms; also fossil in the rocks of 

 Barbados. 



5. Lithocyclia heteropora, n. sp. 



Phacoid shell two and a third times as liroad as the medullary shell, surrounded by five to 

 nine chambered rings, which are divided by piercing radial beams each into fifty to seventy chambers. 

 Margin of the disk smooth. Pores very different in the inner and outer pait of the surface ; in the 

 jihacoid shell larger, regular, circular, eiglit on its radius, in the chambered periphery very small and 

 irregular, somewliat spongy. 



Dimensions. — Diameter of the disk (with nine rings) 0'2, of the phacoid shell 013, of the 

 medullary shell 0'055. 



Hahitat. — Pacific, central area, Station 263, depth 2650 fathoms. 



Genus 197. Coccodiscus,^ Haeckel, 1862, Monogr. d. Radiol., p. 485. 



Definition. — C o c c o d i s c i d a M^itli simple circular margin of the disk, without radial 

 appendages. Medullary shell double. 



The genus Coccodiscus has quite the same form and structure as the preceding 

 Jjithocyclia, and differs from it only in the doul)le medullary shell, composed of two 

 concentric latticed spheres ; sometimes the inner medullary shell is spherical, the outer 



' CoccodisCHS = Disk with nucleus ; xokxo;, oIcko;. 



