ECHINONEUS CYCLOSTOMUS. 43 
in the sand and are found only by sifting the sand. A flour scoop proved the 
best implement for digging up the sand, and then passing it through a set of 
sieves, the lowest having a very fine mesh. By the use of such sieves some small 
specimens were obtained which it would have been practically impossible to 
have obtained in any other way. In rare instances, specimens were found 
clinging to the rock overturned, but as they were clinging by the abactinal tube- 
feet, it is evident they were only accidentally pulled up with the rock. Careful 
examination of the sand around the rock-fragments (not beneath them) and 
in areas not under rocks always failed to reveal Echinonéus or Brissus. It seems 
as though rock-fragment were the essential factor in determining the exact 
habitat. This may however be true in very shallow water only, for the Litch- 
field sand-flat is covered at high tide by only 1-3 feet’ of water and at low tide 
much of it is bare. 
‘As in many regular Echini, the tube-feet of Echinonéus are used to hold 
sand-grains and particles of dirt close against the test, thus more or less con- 
cealing the animal. 
“‘For this reason specimens only a few millimeters long are very hard to see, 
the large flat grains of sand (derived apparently from calcareous Algae) afford- 
ing an admirable means of concealment. When placed in a glass dish of sea- 
water, without any sand, Echinonéus stretches the abactinal tube-feet out 
far beyond the spines as though hunting for something, but after a short time, 
they are retracted below the spines. If sand is present the animal soon covers 
itself. In or on a sufficient amount of sand, the movement of the animal is 
very evident. Both spines and tube-feet appear to be used in locomotion. 
“The color of Echinonéus is whitish with a more or less marked reddish 
tint. One small specimen was found the whole abactinal surface of which was 
deep red. The tube-feet are clear, translucent red (more rose than scarlet, 
yet not a rose-red), in marked contrast to the test and spines, so that the ambula- 
cra stand out sharply. The color seems to be very easily affected by reagents, 
becoming much darker than normal in alcohol, or glycerine. Formalin turns 
the red shades to yellowish green ultimately becoming greenish yellow. A 
strong salt solution (NaCl in fresh-water) kept the colors fairly well for a short 
time (2448 hours) but specimens so treated afterwards became dingy brownish. 
Mixtures of aleohol and formalin and of alcohol, formalin and glycerine were 
of no avail, whether made up with fresh- or sea-water. The specimens which 
are now nearest natural color are certain young ones treated only with pure 
alcohol or pure glycerine. 
