194 IOWA STUDIES IN NATURAL HISTORY 
with their internal fittings on slight provocation.’’ The intes- 
tines were filled with the sandy mud of the eelgrass bottoms. 
Euapta lappa (Miller) is in many respects the most inter- 
esting holothurian that the writer has ever seen. A fully ex- 
tended specimen sometimes reaches the length of two feet and 
looks more like an enormous worm than anything else. It is 
quite translucent, being thinner walled than most species, and 
the body is longitudinally striped with reddish brown bands 
and bears numerous rounded nodules arranged in annular ser- 
les; but these disappear completely when the animal is entirely 
extended, or in parts of its length which are extended, only to 
reappear instantly upon contraction. Waves of such contrac- 
tion pass rhythmically along its length. It is the most active 
holothurian by far that I have ever seen and is really a beauti- 
ful object when in the aquaria and in vigorous motion. The 
feathery tentacles are in constant activity, waving this way and 
that, lengthening and shortening, bending gracefully, their 
frilled edges a constant play of activity; while the whole body 
is in rhythmical movement, bending, twisting, elongating, re- 
tracting, and at the same time pulsating with the waves of re- 
traction already referred to, during which the hemispherical 
nodules appear and disappear as if by. magic along its whole 
length. The transparency of the body walls gives a peculiar 
delicacy that we do not usually associate with the ordinarily 
unattractive ‘‘sea cucumbers.’’ Mr. Ricker took a movie of one 
of these animals in action that will doubtless prove of unusual 
interest. 
These creatures belong to the apodous group, being devoid of 
the ambulacral feet characteristic of most of the more familiar 
forms. Strangely enough, although footless, it moves with 
much more freedom and speed than its heavier relatives. It was 
found commonly in shallow water, often lurking under rocks 
associated with sea-urchins and serpent stars. 
Its footless condition is compensated for by the possession of 
several peculiar features. Doubtless the hemispherical and tem- 
porary nodules already referred to give it a hold on the stones 
between which it worms its way, and its extreme distensibility 
enables it to go through quite narrow holes and eracks, while 
the waves of contraction serve to push it rapidly along either on 
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