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THE VOYAGE OF H.M.S. CHALLENGER. 



I. Subfamily 



Xiphostylida. 

 (Spherical shell simple. ) 



II. Subfamily 



Sphaerostylida. 

 (Two concentric spheres.) 



III. Subfamily 



Amphistylida. 

 (Three concentric spheres. ) 



Synopsis of the Genera of StylospJicerida. 



Polar spines free, without f Both spines equal, 



connecting ring on the j 



j distal ends. ) Spines different in size 



j |_ or form, . 



[ Both polar spines united by a circular or elliptical ring, 



( Botli spines equal, 



Polar spines free. -{ . ,., , . 



Spines different in size 



[ or form, . 



Both polar spines united by a circular or elliptical ring, 



f Both spines equal, 



Polar spines free. 



1 Spines different in size 

 [ or form, . 



IV. Subfamily 



Cromyostylida. 

 (Four concentric spheres.) 



V. Subfamily \ 



Caryostylida. V 



(Five or more concentric ( 

 spheres. ) 



Both polar spines united by a circular or elliptical ring, 



Both spines equal, 

 Spines different, . 



Polar spines free. 



Polar spines free. 



Both spines equal, 



VI. Subfamily 



Spongostylida. 

 (Spherical shell partially or 

 wholly of a spongy structure. ) 



Shell a solid spongy sphere without central medullary 

 shell, . 



(One central medullary 

 shell, 

 . 



lary shells. | Two concentric medul- 



(_ lary shells, 



45. XipliosplicRra. 



46. Xiphostylus. 



47. Saturnalis. 



48. Stylosphcera. 



49. Sphcerostylua. 



50. Saturmdus. 



51. Amphispluxra. 



52. Ampliistylus. 



53. Saturninus. 



54. Stylocromyum. 



55. Cromyostylus. 



56. Caryostylus. 



57. Sponr/olonche. 



58. Spongostylus. 



59. Spongostylidium. 



Subfamily XIPHOSTYLIDA, Haeckel, 1881, Prodromus, pp. 449, 450. 

 Definition. S tylosphserida with one simple spherical lattice-shell. 



Genus 45. Xiphosphcera, 1 Haeckel 1881, Prodromus, p. 450. 



Definition. S tylosphserida with one single lattice -sphere and two free 

 spines of equal size and form. 



The genus Xiphosphcera is the most simple form of all Stylosphserida, and may 

 be regarded as the common ancestral form of this family. On the surface of a simple 



= S word-sphere ; i/ipoj, alpaca. . 



