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



Dimensions. Length of the spines 0'3 to 04, greatest breadth 0'015 ; length of the apophyses 

 0-03 to 0-05. 



Habitat. Central Pacific, Station 270, surface. 



6. Xiphacantha ancorata, n. sp. 



Spines slender, four-sided prismatic, gradually thickened from the narrow base towards the 

 short, simple, pyramidal apex. Base with large wing-cross. Four apophyses on the distal end, 

 immediately below the pyramidal apex, falcated, strongly recurved, like an anchor with four strong 

 teeth. 



Dimensions. Length of the spines 0'4 to - 5, basal breadth O'OOS, distal breadth - 015 ; length 

 of the apophyses 0'04. 



Habitat. Indian Ocean, Madagascar, Eabbe. 



Subgenus 2. Xiphacanthidium, Haeckel. 



Definition. Apophyses of the radial spines broad, compressed, wing-shaped, formed 

 like a large thin plate. Edges of the spines commonly broad, strongly prominent. 



7. Xiphacantha stauroptera, n. sp. 



Spines four-winged, from the middle part little thinner towards both ends. Apex simple 

 pyramidal. Base with small wing-cross. Four apophyses wing-shaped, isosceles triangular or 

 truncated quadrangular; their base is about half as broad as their length, and occupies in the basal 

 half of each spine about one-sixth to one-eighth of its length. 



Dimensions. Length of the spines 01 to 015 ; greatest breadth (diagonal of the cross of the 

 apophyses) 0'006 to 0'009. 



Habitat. South Atlantic, Station 332, surface. 



8. Xiphacantha trigonoptera, n. sp. 



Spines four-winged, tapering rapidly from the broad middle part towards both ends. Apex 

 simple pyramidal. Base with a small wing-cross. Four apophyses equilateral triangular ; their 

 base occupies the middle of each spine, extending to about one-fifth of its length. 



Dimensions. Length of the spines 015 to - 2, greatest breadth (diagonal of the cross of the 

 apophyses) 0'06 to 0'08. 



Habitat. Central Pacific, Station 272, surface. 



9. Xiphacantha macroptera, n. sp. 



Spines four-winged, from the broad middle part gradually thinner towards both ends. Apex 

 simple pyramidal. Base with small wing-cross. Four apophyses wing-shaped, very long and broad, 



