EEPORT ON THE EADIOLARIA. 597 



Subgenus 1. Spongastrella, Haeckel. 



Definition. — Cross formed by the four arms regular, rectangular, with the arms 

 of equal size and equidistant. 



1. Spongaster tetras, Ehrenberg. 



Spongaster teiraa, Ehrenberg, 1872, Abhandl. d. k. Akad.^d. Wiss. Berlin, p. 299, Taf. vi. (iii.) 



fig. 8. 

 Dictyocoryne tetras, Haeckel, 1862, Monogr. d. Radiol., p. 469.' 



Arms at equal distances, forming a rectangular, regiilar cross, club-shaped, about twice as long as 

 the diameter of the square central disk and eight times as long as broad at their base. Distal ends 

 rounded, perfectly enclosed by the complete patagium, which forms a regular square, with shghtly 

 concave sides. 



Dimensions. — Eadius of the arms 012, distal breadth 0-03, basal breadth 0015 ; length of the 

 square side 0-2. 



Habitat. — Cosmopolitan; Atlantic, Indian, Pacific, surface and in various depths. 



2. Spongaster quadratus, n. sp. 



Arms at equal distances, forming a regular, rectangular cross, club-shaped, about four times as 

 long as the diameter of the central circular disk, and five times as long as broad at the base. 

 Basal third of the arms square ; distal two thirds triangular, three times as broad, with a truncated 

 distal end. Patagium complete, perfectly enveloping the arms, and bordered by an elegant, radially 

 striated, broad edge, forming a regular square. (Similar to Histiastrum quadratum, PI. 46, fig. 4, 

 but quite spongy.) 



Dimensions. — Radius of the arms 0-15, distal breadth 006, basal breadth 0-02 ; length of the 

 square side 0".25. 



Habitat. — Pacific, central area. Stations 270 to 274, depths 2350 to 2925 fathoms. 



3. Spongaster criiciatus, n. .sp. 



Arms at equal distances, forming a rectangular, regular cross, lanceolate, three times as long as 

 broad and as the diameter of the central circular chsk. Ends of the arms provided with a short 

 conical spine. Patagium incomplete, enveloping only the basal half of the arms, forming a regular 

 square with concave sides. 



Dimensions. — Eadius of the arms 018, greatest breadth 005 ; length of the square side 0'2. 



Habitat. — South Pacific, Station 288, surface. 



