Description of the Argulus Catostomi. 301 
margins to become tubular; and that the enclosed spicula represents 
the mandibles. ‘The part which we have called the lower lip, is 
analogous to the /anguette; and the maxille with the long bones 
thereto attached are not unlike these organs as usually observed. 
In the Argulus foliaceus the entire oval mass, which we have above 
described, is assumed by Jurtne tobe the heart ; which we are com- 
pelled to consider a total error. The palpitation, or alternate con- 
traction and dilatation, which he speaks of, appears to us nothing 
more than the motion of the maxille, which just before death often 
becomes incessant, and in the instance mentioned by him was prob- 
ably caused by the “alcoholic asphyxiation.” 
_ The anterior legs are short, hollow, flexible cylinders, containing 
four tumid membranes attached near the center of these legs at the 
bottom and extending up along the sides. By means of these the 
animal is enabled to exhaust the cavities and thus attach itself to its 
prey. The extremity terminates in a broad, circular, horizontal 
rim, with a margin nearly entire, provided with about eighty bony 
rays, each composed of eleven joints, (Fig. 6.) When the animal 
is nearly dead, this rim assumes a vertical position, and from the 
relaxing of the membrane appears to have a crenated margin.* 
hese legs in their natural position are at right angles with the body 
and consequently the lower portions are concealed by the termina- 
ting border. On fig. 1, may be seen lines proceeding from between 
the base of the anterior antenne which probably mark the limits of 
a muscle connected with these legs. 
The prehensile legs arise below and on each side of the mouth, 
and are six-jointed. The thigh or second joint, is short, massive 
and irregular, and its posterior margin is occupied by three broad 
and flat teeth, with interstices about equal to half the average width. 
These teeth are irregularly quadrilateral with rounded angles. In 
this respect this speciés differs from the A. foliaceus, in which 
there are four narrow, acute, and incurved teeth about the base of 
this joint. 
On the lower surface is a triangular, subconvex elevation, covered 
. With papilla. The third joint gradually tapers towards its apex, 
where it is papillose ; the fourth joint is shorter than the aig and 
* Jurine’s figure of this rim or disk errs in exhibiting it in the vertical position 
as that which appears during life: this is never observed except when the powers 
of life are nearly exhausted. e 
