78 IOWA STUDIES IN NATURAL HISTORY 
eye’’ fish. This roach is an Isopod, the largest specimen se- 
sured being two inches long and thick in proportion. As one 
would expect from its parasitic habit, it is entirely colorless, 
or rather an ivory white. It is also apparently eyeless, another 
effect of a parasitic life, I suppose; and is provided with seven 
pairs of remarkably strong claw-like appendages, with which 
it maintains its relentless grip on the tongue of its unfortunate 
host. Near the base of each of these appendages is a strong 
flattened process reaching downward and backward. The basal 
joint is provided with a strong elevated ring surrounding 
a cup-like cavity which may act as a sucker to still further in- 
sure the fixation of this really terrible parasite. 
Imagine the discomfort of a poor fish with such a creature 
permanently fixed in its throat at the base of the tongue, and 
holding on with relentless tenacity! A wood-tick eight inches 
long lodged in a man’s throat would convey some idea of the 
‘“horse-eye’’ afflicted with a roach. 
The commonest crustacean about Pelican Island, and one of 
the hardest to secure, was the ‘‘Sally lightfoot’’ (Grapsus 
grapsus). This is an extremely flattened creature of consider- 
able size, some specimens attaining a spread of ten inches, al- 
though the carapace is but two and one-half inches wide. Its 
eolor is dull dark red, mottled with grayish and yellowish below. 
The chele are brilliant vermillion with white tips. This spe- 
cies was abundant all along the sea-wall built of blocks of coral 
rock which was a mottled dark gray and earth color from long 
exposure. Grapsus is the liveliest in its movements of any crab 
that I have seen, scuttling into the crevices of the rock at the 
least evidence of danger; its thin body fitting snugly into sur- 
prisingly small eracks, and dashing about with remarkably 
agility. Although the commonest crab of the region and almost 
always in evidence, we found it exceedingly hard to secure 
specimens. Albert, our diver, was equal to the occasion, how- 
ever, and would get into the water by the sea wall and show 
agility equal to that of the ‘‘Sally light-foots,’’ thus securing 
a fine series of this interesting species. The moray, as already 
mentioned, is equally quick and we saw one pick a erab off the 
sea-wall fully as expertly as did Albert. 
