STRUCTURE OF CRINOIDS. 
from one hundred to 
one thousand fathoms 
in the North Atlantic 
and Floridan seas, 
and is a characteristic 
member of the abyssal AWS 
This crinoid Was 
fauna. 
consists of a jointed 
stalk, a cup-shaped 
body (calyx), from 
the edge of which 
from five to seven 
{the number varies) 
arms (brachia) radi- 
ate, which subdivide 
into a double alter- 
nate series of pin- 
nule. The mouth is 
situated in the centre, 
while the anus is situ- 
ated on a conical pro- 
jection on one side of 
the oral disk, between 
the bases of two of 
the arms. &. Raw- 
sont Pourtales occurs 
in from eighty to one 
hundred and twenty 
fathoms at Barba- 
does. 
In Holopus, a short, 
stout form with no 
true stalk, but at- 
tached by a broad en- 
crusting base, there 
are ten arms originat- 
ing from five axial 
joints. ‘‘ When con- 
tracted the arms are 
ene Onn Ove seg ae 
ease ale 88 Ora one 
oe Sans one 
185 
Ne 
Fig. 128.—Rhizocrinus lofotensis Sars, twice natural 
ize.—After Wyville Thompson. 
