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



7. Acanthometron pellucidum, J. Miiller. 



Acanthometra pellucida, J. Miiller, 1858, Abhandl d. k. Akarl. d. Wiss. Berlin, p. 47, Taf. xi. 



figs. 1-3. 

 Acanthometra pellucida, Haeckel, 1862,'Monogr. d. EadioL, p. 378. 



Spines cylindrical, very thin and long, needle-shaped, nearly of equal thickness in their whole 

 length. Central base with a small fulcral pyramid, without leaf-cross. Distal apex bifid or 

 bifurcate, with two thin parallel teeth. Central capsule pellucid, colourless, with yellow pigment- 

 bodies. (Differs from Acanthometron elasticum mainly in the bifid apex.) 



Dimensions. Length of the spines 01 to 0'3, breadth O002 to 0'004 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Pacific, surface. 



8. Acanthometron wageneri, Haeckel. 



Acanthometra wageneri, Haeckel, 1862, Monogr. d. Eadiol., p. 378. 



Spines cylindrical, in the thickened outer half about twice as broad as in the thin inner half. 

 Central base a little thickened, with large fulcral pyramid, but without leaf-cross. Distal apex 

 bifid, with two divergent, often denticulated teeth. Central capsule pellucid, with yellow pigment- 

 bodies. (Differs from Acanthometron dolichoscion mainly in the bifid apex.) 



Dimensions. Length of the spines - 2 to O5, breadth in the inner part 0'003, in the 

 outer 0-006. 



Habitat. Adriatic Sea ; Triest, Wagner ; Corfu, Haeckel, surface. 



Subgenus 2. Phyllostaurus, Haeckel, 1862, Monogr. d. Eadiol., p. 381. 



Definition. Spines at the central base with a broad leaf-cross, composed of four 

 prominent triangular lamellae ; the meeting edges of the neighbouring lamellae are 

 propped one upon another in such a manner that there are formed twenty-two hollow 

 pyramidal spaces or compartments (compare p. 721). 



9. Acanthometron siculum, Haeckel. 



Acanthometra sicula, Haeckel, .1862, Monogr. d. Eadiol., p. 382, Taf. xvii. figs. 1, 2; Taf. xviii. 

 fig. 8. 



Spines elongate, conical, tapering gradually from the thick base towards the simple distal 

 apex. Conical circular base supported by a basal leaf -cross of double the breadth. Central 

 capsule yellowish-brown, opaque. 



Dimensions. Length of the spines 0'3 to 0'4, basal breadth O'OOS to 0'012, leaf-cross 0'024. 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Pacific, surface. 



