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



Subgenus 2. Stauracanthidium, Haeckel. 



Definition. Apophyses of the radial spines forked, each with two divergent 

 terminal branches, which are not parallel to the cross axes of the quadrangular spine. 



8. Stauracantha stauraspis, Haeckel. 



Dorataspis polyancistra, juvenis, Haeckel, 1862, Monogr. d. Eadiol., p. 418, Taf. xxi. fig. 7. 



Spines slender, quadrangular prismatic, with simple apex and pyramidal base (without 

 basal leaf-cross) ; with four slender apophyses, which are simply forked in the outer third. 

 Each apophysis with two recurved fork branches. 



Dimensions. Length of the spines 012, breadth 0'004; distance of the apophyses 0'06. 



Habitat. Mediterranean (Messina), surface. 



9. Stauracantha bifurca, n. sp. 



Spines stout, four-winged prismatic, with pyramidal apex and pyramidal base (without 

 leaf-cross) ; in their middle with four compressed, little curved apophyses (convex on the outer, 

 concave on the inner edge), which are simply forked at the end. Each apophysis with two short 

 straight fork branches. 



Dimensions. Length of the spines 0'2, breadth O006 ; distance of the apophyses - 08. 



Habitat. Central Pacific, Station 266, surface. 



10. Stauracantha quadrifurca, n. sp. (PI. 130, fig. 4). 



Spines slender, four-sided prismatic, with simple apex and pyramidal base (without leaf -cross) ; 

 with four slender apophyses, which are doubly forked about in their middle. Each apophysis 

 with four short and thin terminal branches. 



Dimensions. Length of the spines 0'2, breadth 0'002 ; distance of the apophyses from the 

 centre 0-08. 



Habitat. South Atlantic, Stations 325 to 330, surface. 



Genus 332. Phatnacantha, 1 Haeckel, 1881, Prodromus, p. 465. 



Definition. A strolonchida with four apophyses on each radial spine, 

 opposite in pairs in cross form, and forming a lattice-plate by communicating branches. 



The genus Phatnacantha has been derived from the preceding Stauracantha by 

 concrescence of the branches of the apophyses. Therefore each spine bears a lattice- 

 plate or a fenestrated shield. If the growing plates of the neighbouring spines 



1 Phatnacantha = Spine with fretwork ; Xctmn, &r.a.6y. 



