148 THE DEPTHS OF THE SEA. [CHAP. Iv. 
arranged vertically, and this peculiar tissue forms a 
complete sheath surrounding a pulpy mass of gra- 
nular horny and sarcodic matter which fills the 
interior. In this inner spongy substance sheaves of 
similarly shaped spicules are likewise arranged ver- 
tically, but much more loosely; and the projecting 
scales forming the head of Thecophora ibla are formed 
by the projecting ends of such sheaves. Among 
echinoderms, Ophiacantha spinulosa was one of the 
Fic. 24.—Zhecophora ibla, WyvILLE THomson. Twice the natural size. (No. 76.) 
prevailing forms, and we were greatly struck with 
the brilliancy of its phosphorescence. Some of 
these hauls were taken late in the evening, and the 
tangles were sprinkled over with stars of the mest 
brilliant uranium green; little stars, for the phos- 
phorescent light was much more vivid in the younger 
and smaller individuals. The light was not constant, 
nor continuous all over the star, but sometimes it 
struck out a line of fire all round the disk, flashing, 
