FACTORS IN THE BEHAVIOR OF OPHIUROIDS 391 
My observations on the ophiuroids found among the coral 
reefs near Loggerhead Key confirm the observations of these two 
investigators and show that these appendages are important both 
in cHmbing and feeding. The ambulacral appendages of Ophio- 
coma riisei seem to be quite well developed when compared with 
those of some other ophiuroids, although they are not so service- 
able in locomotion as those of the starfish. Grave (1900) has 
found that Ophiura brevispina uses the tube-feet in ordinary loco- 
motion by fitting them into the irregularities of the surface, thus 
forming hold-fasts for the rest of the arm to pull against. The 
same behavior was observed in Ophiocoma riisei, but as in the 
case of Ophiura brevispina, when an individual moves fast it does 
so by the stroke movement of the rays and the ambulacral ap- 
pendages do not seem to aid. Jennings (1907) has shown that 
in the starfish, Asterias forreri de Loriol, the appendages are used 
in a somewhat similar manner to the human leg. This is prob- 
ably true for all starfishes, but only to a small extent for the ophi- 
uroids. When an individual moves slowly such movements of 
the tube-feet may be seen but they are not very important in 
locomotion. 
Until the publication of the observations of von Hj. Ostergren 
(1904) on the climbing of Ophiocoma nigra it was generally 
supposed that the brittle-stars did not use their tube-feet in a 
sucker-like manner. My study of Ophiocoma riisei shows that 
while this form has no definite suckers, such as we find at the end 
of the tube-feet of starfishes and sea-urchins, yet its tube-feet have 
an adhesive function which is brought into play principally while 
the creatures are climbing up rocks or other vertical surfaces. 
If a specimen of Ophiocoma riisei is placed with its oral surface 
against the side of a glass aquarium filled with sea-water and held 
there for a few seconds until the tube-feet can be applied to the 
glass the animal will fasten itself and remain for some time. Close 
examination with a lens will show that many of the ambulacral 
appendages have their tips closely pressed against the glass, and 
that often when they are drawn away they loosen their hold with 
a little jerk, showing that something was holding them. No 
adhesive matter could be found at the ends of the tube-feet nor 
