CHARACTERISTIC DEEP-SEA TYPES. — OPHIURANS. 113 
wash inereases the already abundant supply of lime, a substance 
that forms nearly the entire weight of some species ( Ophiomas- 
Fig. 397. — Ophiomyces frutectosus. 3. 
tus secundus, Fig. 398). These conditions naturally give rise 
to much variety in form, and to a great abundance of individu- 
Fig. 398. — Ophiomastus secundus. 5, 
als, The nine species mentioned by Müller and Troschel, in 
1842, as belonging to this area, have increased to one hundred 
and fifty-five, which are distributed at various depths. On the 
flats and reefs, near islands and keys, may be found colonies of 
Ophiothrix, blue, green, or red, with their translucent thorny arm- 
spines, and the humble Ophiactis swarming on great sponges; 
while here and there a yellow or vermilion star marks the soft 
Ophiomyxa flaccida. To the brown gorgonians clings the large 
Ophiocoma, similar in color; and sometimes a Medusa-head, 
whose branching arms excited the wonder of old Rondelet, 
twines about the thicker stems. These and their companions, 
living in a strong light, and in warm shallow water, present 
brilliant and well-marked colors. Nor are those that inhabit the 
dark and çold depths of the ocean always pale; on the contrary, 
many are of a bright orange or red. They are peculiar, how- 
ever, in that their colors generally fade in-alcohol; and in an 
alcoholic collection the shallow species may readily be distin- 
guished by their brighter coloration. 
