LIVING SPECIKS. 
4;l;5 
tJie existing family of star-fislies, and approach 
iiiost nearly to the Comatiila ; (see Miller’s Cri- 
Ooidea, PI. 1, and p. 127): the bony skeleton 
Constitutes by far the largest portion of these 
animals. In the living species this bony frame- 
"’ork is invested with a gelatinous membrane, 
Accompanied by a muscular system, regulating 
movements of every bone. Although, in the 
dossil species, these softer parts have perished, 
yet an apparatus for muscular attachment exists 
en each individual bone.* 
The calcareous joints which compose the fingers 
of the P, Europmus, together with their tentacula. 
Are capable of contraction and expansion in 
every direction; at one time spreading ouPvards, 
^ike the Petals of an open flov'er (PI. 52, Fig. 2'), 
And at another rolled inwards over tlie month, 
like an unexpanded bud ; the office of these 
ergans is to seize and convey to the mouth its 
destined food. Thus the habits of living animals 
illustrate the movements and manner of life 
Af the numerous extinct fossil members of this 
§reat family, and afford an example of the va- 
lidity of the mode of argument, to which we are 
obliged to have recourse in the consideration of 
AXtinct species of organic remains. In this pro- 
cess we argue backwards, and from the mecha- 
nical arrangements that pervade the solid portions 
See the tubercles and corrugations on the surfaces of the 
engraved at PI. 52, Figs. 7, 9, 11, 13, 14, 15, 16, 17. 
O. 
F F 
