ARGULTJS. 
249 
peculiar construction. They are in the form of short, 
hollow, flexible cylinders ; the pedicle by which they are 
attached to the animal being thick and muscular, and the 
extremity terminating in a broad, circular, horizontal rim, 
almost cartilaginous, having a membranous margin, fringed 
all round with numerous rays, which, according to Dana 
and Herrick, are many-jointed. Four muscles are attached 
to the base of each of these organs, and extend up the 
sides. By this organization the animal can make use of 
them as real suckers , or cupping-glasses, to fasten itself 
to the fish upon which it lives, and also to walk with, 
when it wishes to change its position. By contracting 
these muscles, it can exhaust the cavity of the sucldng- 
disc, producing a vacuum, and thus enabling it to adhere 
firmly to the surface upon which it is placed. When it 
wishes to change its place, it relaxes the muscles first of 
one sucker, carrying it forwards, and then the other, alter- 
nately, as was long ago observed by Loefling. The second 
pair of ambulatory legs, or third pair of foot-jaws (t. XXXI, 
f. g), arises immediately below these suckers, and is very 
different in conformation. They are somewhat cylin- 
drical, and are composed of five articulations. The first 
two are much larger than the others, have their surface 
roughened with small spines ; and at the base of the first 
joint, we see three strong teeth. The last joint gives off 
at its extremity two small hooks. These organs are called 
the prehensile feet by Dana and Herrick, and no doubt 
they do assist the animal to secure itself more firmly in 
its position. The natatory feet are four pairs, arising in 
a series on each side of the thorax, and partly covered by 
the lateral portions of the carapace. The first three pairs 
(t. XXXI, f. consist each of a large fleshy peduncle, or 
basilar portion, which is obscurely divided into two joints, 
and gives off at its extremity two long branches, beauti- 
fully fringed, with transparent and delicately plumose 
cilia ; while a third shorter branch, equally plumose, 
arises from the base of the two preceding, and is curved 
backwards and inwards. The fourth pair (t. XXXI, f. kj) 
