198 IOWA STUDIES IN NATURAL HISTORY 
a little water, which is replenished with air-charged foamy 
brine each time a breaker cascades back into the sea. I noticed 
that the tentacles are kept expanded in such little pools and I 
thought at first on account of their large size that the animals 
were one of the Cucumariidz. In hollows of sufficient size, sev- 
eral animals were wedged tightly together after the manner of 
the tiny Cucumaria curvata of the Monterey region. They are 
difficult to dislodge, and it is easy to see how the unusual num- 
ber of tube-feet aid the animal in clinging when the clawing 
waves can erode away cliffs. There is usually a plentiful growth 
of short tough kelp where these holothurians live. This kelp 
overhangs the edges of the little basins in which two or three of 
the animals are demiciled in such a way as practically to hide 
them in some cases. Animals five to seven inches long. A color 
variation: clear dark warm brown. 
Holothuria rigida Selenka. Under the rocks which rested in 
the sand of Falmouth Harbor and which were never uncovered 
by the tide this sluggish species lives. Possibly it comes out at 
night, but was deeply buried in the day and not many were 
found. Sand-colored, with a row of brownish spots along the 
back and a rusty patch or stain on the whitish ventral surface; 
dorsal papille sparse and slender; tentacles small, white. In 
the aquarium it was very sluggish, both by night and by day. 
It is covered with sand grains all over. 
Holothuria surinamensis—(variety). A slender, brown, yel- 
low-tentacled species, exceedingly common at Falmouth Harbor 
in shallow water, where it fairly swarms among corallines and 
under stones in the eel-grass area. It is found where the water 
has receded at low tide, and hence is very tolerant to heat and 
exposure generally, and owing to its tough constitution is more 
difficult to kill with narcotizing reagents than any other species 
except Stichopus mobi. In life the animals are usually stained 
with a coating of fine silt or mud which adheres to their skin 
and partly obscures the rich brown coloring, upon which are 
marbling and spots of dark brown. The papille are rather 
prominent, unequal, and pointed. In aquaria they are rather 
restless. The shallow water in which they occur becomes very 
warm at mid-day and sometimes the animals are washed up on 
the beach or rolled around the edge, kept in motion by a ripple. 
