468 THE VOYAGE OF H.M.S, CHALLENGEE. 



5. Astrocyclia heterocycla, n. sp. (PI. 36, fig. 8). 



Phacoid shell two and a half times as broad as the medullary shell, surrounded by three rings 

 of unequal breadth, the first ring as broad as the second and third together. They are divided by 

 fifty to sLxty jjiercing radial beams into chambers, which are square in the second and third rings, and 

 half as large as in the first. The radial beams are alternately thicker and thinner, prolonged into 

 short marginal sjDines. Pores subregular, circular ; eight on the radius of the phacoid shell, two on 

 the breadth of the first ring, a single one on each chamber of the second and third rings. 



Dimensions. — Diameter of the disk (with three rings) 0"2, of the phacoid shell 0'12, of the 

 medullary shell 0-0 5. 



Habitat. — Equatorial Atlantic, Station .348, deptli (2450) fathoms ; also fossil in Bai-bados. 



Genus 203. Coccocyc/ia,^ Haeckel, 1881, Prodronms, p. 458. 



Definition. — Co c cod is ci da with numerous (five or more) solid radial spines on 

 the margin of the circular disk. Medullary shell doulile. 



The genus CoccocycUa has the same form and structure as the foregoing Astrocyclia, 

 and differs from it only in the double concentric medullary shell. It bears therefore to 

 tlie latter the same relation as Coccodiscus does to Lithocyclia. 



1. Coccocylia Ihiantha, n. sp. 



Phacoid shell three times as broad as the outer and ten times as broad as the mner medullary 

 shell, connected with both by six equidistant piercing radial beams. The margin of the phacoid 

 sliell is surrounded by one or two equatorial rings, each as broad as the outer medullary shell, and 

 divided by thirty to forty radial beams into narrow chambers. Pores subregular, circular, about nine 

 to ten on the racUus of the phacoid shell, three to four on the breadth of each ring. Margin of the 

 disk cihated, with six regularly disposed radial spines as prolongations of the inner six piercing 

 beams. Each spine cylindrical, delicately crenulated, about as broad as the inner medullary shell, 

 and once to twice as long as the diameter of the wliole disk, elegantly undulated, with a conical 

 terminal point. 



Dimensions. — Diameter of the disk (with two rings) 0"32, of the phacoid shell 0-2, of the outer 

 medullary shell 0'06, of the inner 0"02. 



Habitat. — Pacific, central area. Station 265, depth 2900 fathoms. 



2. Coccocylia heliantha, n. sp. (PI. 36, figs. 5, 6). 



Phacoid shell two and a half times as bruad as the outer and six times as broad as the inner 

 medullary shell, surrounded by six to eight rings of nearly equal breadth, tlie outer somewhat 

 smaller. They are divided by fifty to sixty piercing radial beams into irregular chambers. Pores 



' (7occoc;/cK(i = Circular shell with nucleus ; *6xx.o:, y.viChia:. 



