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



Subgenus 3. Raphidodrymus, Haeckel. 



Definition. Pores of the spherical shell irregular, of different 'size or form. Radial 

 spines arising from all the nodal-points of the network. 



18. Acanthosphcera capillaris, n. sp. 



Shell thin walled, with irregular polygonal meshes, twelve to twenty times as broad as the bars ; 

 eight to ten on the radius. Eadial spines bristle-shaped, arising from all the nodal-points of the 

 network, about as long as the diameter of the largest meshes. 



Dimensions. Diameter of the shell 015 to 0'2, pores 0'012 to O02, bars O'OOl ; length of the 

 spines 0'02. 



Habitat. Central Pacific, Stations 260 to 274, surface. 



19. Acanthosphcera arctica, n. sp. 



Shell thin walled, with irregular roundish, polygonally framed meshes, three to four tunes as 

 broad as the bars. Eadial spines arising from all the nodal-points of the network, pyramidal at 

 the base in the distal half bristle-shaped, as long as the radius. 



Dimensions. Diameter of the shell 0'12, pores O'OOG to O'OOS, bars 0'002 ; length of the 

 spines 0'07. 



Habitat. Arctic Ocean, Greenland (in the stomach of Periphylla hyadnthina). 



20. Acanthosphcera antarctica, n. sp. 



Shell thick walled, with irregular, roundish pores, about as broad as the bars. Radial spines 

 arising from all nodal-points of the network, conical at the base, half as long as the radius. 



Dimensions. Diameter of the shell 0'15, pores and bars 0'005 to O'OOS ; length of the 

 spines 0'04. 



Habitat. Antarctic Ocean, Station 157, depth 1950 fathoms. 



Subgenus 4. Rhaphidosphcera, Haeckel, 1881, Prodromus, p. 450. 



Definition. Pores of the spherical shell irregular, of different size or form. Radial 

 spines scattered at intervals, not at all the nodal -points. 



21. Acanthosphcera echinoides, Haeckel. 



Cyrtidosphwra echinoides, Haeckel, 1865, Zeitschr. f. wiss. Zool., xv. p. 367, Taf. xxvi. fig. 5. 



Shell thin walled, with irregular polygonal or more roundish pores of very different size. Forty 

 to fifty very large meshes, separated by rows of much smaller meshes. Radial spines forty to sixty, 

 half as long as the shell radius, bristle-shaped, with conical bases. 



