STAR-FISHES. 
97 
ridges, bearing long, slender diverging spines, some seven 
°r eight in each perpendicular series on each side. 
These spines, when examined with a microscope of high 
power, present very beautiful objects. We have this in- 
stant been charmed by the appearance of several of them 
magnified about two hundred diameters. When the rays 
°f sunlight are reflected from them, they resemble the 
most elegant taper columns or obelisks, roughened with 
projecting points shooting perpendicularly upwards, and 
arranged in parallel rows throughout the whole length ; 
and, as tho whole is composed of a substance of brilliant 
transparency and exquisite polish, the points sparkle in the 
light as if the whole column were sculptured in orystal. 
Professor Edward Forbes truly remarks of a spine of this 
Brittle-star highly magnified, that it exhibits “ a structure, 
the lightness and beauty of which might serve as a model 
for the spire of a cathedral.” 
The internal structure of the spines is no less admirable 
than their external beauty. The calcareous substance of 
which they are composed,— a carbonate of lime, mixed 
with a minute proportion of the phosphate, according to 
Professor Grant, — which, as we have already observed, re- 
sembles in appearance crystal or flint-glass, is not solid, 
but is excavated by a multitude of apparently empty cells, 
having no connexion with each other, but set in rows and 
series more or less exact. We notice this because it is the 
plan upon which all the calcareous parts of the animals of 
this class are modelled j the plates of the globular case of 
the Sea-urchin, those of tho Brittle- star, the spines of both, 
the tubercles of the Cross-fish, the stems and skeletons of 
the singular Pedicellarice , which we shall presently have 
G 
