REPORT ON THE RADIOLARIA.. 541 



4. Stauralastrum davigeritm, n. sp. 



Anns twice as long as broad, in their distal half lenticular, nearly circular, twice as broad as 

 in their square proximal half ; their distal breadth equals the diameter of the central disk, which 

 exhibits three to four rings. Edges of the arms concave. 



Dimensions. — Radius of each arm 0'2, basal breadth 0'04, distal breadth O'OS. 



Habitat. — Pacific, central area, Station 268, depth 2900 fathoms. 



5. Stauralastrum dilatatum, n. sp. 



Arms of nearly equal length and breadth, at their convex distal end three times as broad as at 

 their narrow base ; their distal breadth three times as large as the radius of the central disk, 

 which exhibits three to four rings. (Eesembles Histiastrum quadrigatum, PL 46, fig. 3, but has no 

 patagium.) Edges of the arms concave. 



Dimensions. — Eadius of each arm 0'15, basal breadth 0"04, terminal breadth 01 2. 



Habitat. — South Pacific, Station 300, depth 1375 fathoms. 



Subgenus 2. Stauralastromma, Haeckel. 

 Definition. — Ends of the arms with one or more terminal spines. 



6. Stauralastrum rhopalophorum, n. sp. (PI. 45, fig. 1). 



Hagiastrum rJiopalophonim, Haeckel, 1881, Prodromus, p. 460. 



Arms cylindrical, eight times as long as broad at their base, at their distal end club-shaped, 

 three times as broad as at their base ; their distal breadth twice as large as the diameter of the central 

 disk, which exliibits two to three rings. Surface thorny, witli larger spines towards the end, and 

 one radial, very strong, angular terminal spine. Edges of the arms parallel. 



Dimensions. — Piadius of each arm (without terminal spine) 0-32, basal breadth 0-03, terminal 

 breadth 01. 



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



7. Stauralastrum antiquum, n. sp. 



Rlwpalastrum sp. Bury, 1862, Polycystins of Barbados, pi. xiv. fig. 5. 



Arms six times as long as broad at their base, in their distal half nearly spherical, three times as 

 broad as in their cylindrical basal half ; their distal breadth nearly equals the diameter of the central 

 disk, which exhibits three to four rings. On the end of each arm one strong, angular, terminal 

 spine. (Diflers from the preceding species by larger central disk and stouter arms, also by less 

 developed spines.) Edges of the arms parallel. 



Dimensions. — EacUus of each arm 0-25, basal breadth 0-04, terminal breadth 012. 



Habitat. — Fossil in the Barbados rocks; and living in the depths of the Central Pacific, Station 

 266, depth 2*750 fathoms. 



