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



insufficient diagnosis Dictyocoryne was identical with his Spongaster (compare my 

 Monograph, p. 467) ; but as the type of this latter genus (Spongaster tetras) figured 

 by him, 1872, had four crossed arms, we retain this genus here separate. 



Subgenus 1. Dictyocorynula, Haeckel. 



Definition. Triangular shell regular, with three arms of equal size and equal 

 distance. 



1. Dictyocoryne profunda, Ehrenberg. 



Dictyocoryne profunda, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 307, Taf. vii. 

 fig. 23. 



Arms of equal size and equidistant, club-shaped, in the outer circular half three times as broad as 

 in the inner cylindrical half, and much larger than the small triangular central disk. Patagium 

 complete, forming an equilateral triangle with rounded corners. 



Dimensions. Eadius of the arms 014, basal breadth 0'025, distal breadth 0'07. 



Habitat. Pacific, Philippine Sea, depth 3300 fathoms, Ehrenberg; Station 198, depth 2150 

 fathoms ; Station 274, depth 2750 fathoms. 



2. Dictyocoryne tetradiscus, n. sp. 



Arms of equal size and equidistant, club-shaped, their outer circular half is quite as large as the 

 circular central disk, and is connected with it by the thin cylindrical inner half, which is scarcely 

 one-fourth as broad. Patagium complete, forming an equilateral triatigle with rounded corners and 

 convex sides. 



Dimensions. Eadius of the arms 016, basal breadth 0'02, distal breadth 0'08. 



Habitat. Pacific, central area, Stations 271 to 274, in 2350 to 2750 fathoms. 



3. Dictyocoryne euchitonia, Haeckel. 



Dictyocoryne euchitonia, Haeckel, 1862, Monogr. d. Radiol., p. 468. 



Arms of equal size and equidistant, lanceolate, twice as long as broad in the distal part, and three 

 times as long as the small circular central disk. Patagium complete, forming an equilateral 

 triangle with pointed corners. (Very similar to JEuchitonia kollikcri, Monograph, 1862, p. 511, 

 Taf. xxxi. fig. 6, but quite spongy, not concentric.) 



Dimensions. Radius of the arms 015, basal breadth 0'03, distal breadth 0'06. 



Habitat. Mediterranean (Messina), Haeckel. 



