60 



THE VOYAGE OF H.M.S. CHALLENGER. 



different cases of regular disposition were observed : (A) two opposite beams in one 

 axis ; (B) four beams, opposite in pairs in two axes perpendicular one to another ; (C) 

 six beams, opposite in pairs in the three dimensive axes ; (D) eight beams, opposite in 

 pairs in the four diagonals of the regular cube ; (E) twelve beams corresponding to 

 the twelve axes of the regular icosahedron ; (F) fourteen beams quite regularly disposed 

 (six corresponding to the three axes of the regular octahedron, eight to the central points 

 of its faces) ; (G) twenty beams (probably corresponding to the twenty corners of a 

 regular dodecahedron) ; (H) thirty -two beams, regularly disposed. Rarely the number of 

 the radial beams is intermediate between these eight cases, and rarely it is higher ; 

 then commonly the disposition is irregular. The regularity of their disposition in the 

 great majority of cases is very remarkable and evident. 



I. Subfamily 



Ethmosphserida. 

 (Shell one siugle latticed sphere.) 



Synopsis of the Genera of Liosphcerida. 



(" Shell-cavity simple, . 

 Pores of the shell simple, j 



not prolonged into free { Shell-cavity withradial 

 tubuli. beams united in the 



centre, 



15. Cenosphcera. 



16. Stiy m ospluera. 



I" Tubuli external, centri- 



Pores prolonged into free | fugal, . .17. Ethmosphcera. 



conical or cylindrical \ 

 tubuli. | Tubuli internal, ceutri- 



[ petal, 



II. Subfamily 



Carposphaerida. 

 (Two concentric spheres.) 



III. Subfamily 



Thecosphserida. 

 (Three concentric spheres.) 



IV. Subfamily 



Cromyosphserida. 

 (Four concentric spheres.) 



V. Subfamily 



Caryosphserida. 

 (Five or more concentric spheres. ) 





18. Sethosphcera. 



19. Carpoyrfuzra. 

 20. 



One shell medullary (intracapsular), the other 

 cortical (extracapsular), 



Both shells cortical (near together), 



f Two shells medullary (intracapsular), one shell 

 cortical (extracapsular), 



One shell medullary (intracapsular), two shells 

 [ cortical (extracapsular), 



I Two inner medullary shells (intracapsular), and two 



I outer cortical shells (extracapsular), . . 23. Cromyoqrficera. 



I Two inner medullary shells, and three or more outer 



21. Thccosjihcera. 



22. Rhodospltcera. 



j 



cortical shells, . 



VI. Subfamily 



Plegmosphnerida. 



(Spherical shell wholly or partially of 

 spongy structure. ) 



, [ Sphere solid, . 

 Spongy sphere without 



latticed medullary \ g , 

 shell in the centre. ' ., 



Spongy sphere with one 

 or two latticed medul- 

 lary shells in the 

 centre. 



One single medullary 

 shell, 



24. Caryosphce-ra. 



25. Sfyptosphcpra. 



26. Plcgmogj/haird. 



27. SpongopUgma. 



Two concentric medul- 

 lary shells, . 28. Sponrjodictyon. 



