STAR-FISHES. 
109 
may be described as a thick head, cleft into three divisions, 
and set on a long, slender, flexible stalk. Through a por- 
tion only of the stalk passes an inflexible shelly support 
like a bone, but there is left a considerable part which is 
perfectly soft, flexible, and highly contractile ; and by the 
motions of this part, the massive head is thrown about in 
all directions with great vivacity. 
Now let us look at the heads of these strange nodding 
creatures. The largest sort has a head shaped something 
like a sugar-loaf, split from the apex to the base into three 
lobes, which gape widely and close together with most 
ferocious snappings. These openings and shuttings of 
the threefold jaws are constantly going on, fitfully and 
without any regularity or agreement ; and most curious 
it is to watch them, and to endeavour (though without 
success) to discover what possible end is accomplished by 
the procedure. 
If we examine these bodies with high microscopic powers, 
little light is afforded on the question of their special 
functions, though they are thus determined to be organic 
appendages of the Echinus. But new admiration is ex- 
cited at their elaborate structure and finish. The head 
consists principally of calcareous substance, which, as well 
as the supporting column of the stalk, is penetrated with 
isolated cells throughout. The bases of the three-lobed 
head are articulated in the most remarkable manner ; and 
the lobes themselves, which are sometimes attenuated to 
three slender pins, are cut along their meeting edges into 
minute teeth, which fit and lock into each other with 
exquisite precision. The whole body and head are in- 
vested with a gelatinous flesh, in which are imbedded 
