o4 IOWA STUDIES IN NATURAL HISTORY 
These were the most common ophiurians, although several 
species were more or less abundant. I have often wondered why 
these, the most actively moving of echinoderms, have no eye- 
spots or organs of vision; while the star-fish, much less highly 
specialized for locomotion, have quite evident pigmented eye- 
spots at the ends of the rays, and even the sea-urchins often have 
what are supposed to be localized organs of vision. The state- 
ment is quite generally made in the classroom that active move- 
ment is accompanied by the development of sensory organs, 
and that there is on the whole a codrdination. between rapid 
locomotion and perfection of sense-organs, particularly organs 
of sight. There is no doubt that this rule holds in a great ma- 
jority of cases; but the serpent-stars offer an exception not 
easily explained. 
One must be careful in overturning these stones or he will 
make an undesirable acquaintance with the ‘‘sea scorpion,’’ a 
large annelid, sometimes as much as a foot long, whose parapodia 
are armed with myriads of poisonous bristles which sting the 
hand, reminding one of the innumerable fine spines of the 
prickly pear. 
The white sea-urchin or ‘‘sea-egg’’ was found in the deeper 
portion of the shallows between Pelican Island and Barbados. 
This is a favorite article of diet with the Barbadians, and is here 
a staple market comestible during the season. It is protected 
by a closed season, and we were particularly requested to study — 
its reproduction and habits in order to suggest appropriate 
measures to increase the supply which seems to be diminishing. 
The small, almost black, E'chinometra are also common, and 
quantities could be secured near the laboratory. A species of 
Chiton clung to the rocks of the sea-wall, but had to be quickly 
and skilfully pried loose or they stuck so fast that even a knife 
would not remove them. They seemed at times to excavate a 
depression in the rocks in which they fit perfectly and from 
which they can not be taken. 
There were also small sea-cucumbers, worms, gastropods, and 
a small nudibranch or ‘‘sea hare.’’ Beautiful anemones with a 
spread of eight or ten inches were attached to some rocks, and 
these often harbored commensal crabs, which lived near their 
bases and were often captured and devoured when they ineau- 
(4 
