Description of a Species of Caligus. 233 
twelve. The outer margin of the dentated portion is provided 
with a narrow corneous transparent edge. These mandibles ex- 
tend backward and pass out of the buccal mass just anterior to the 
lateral projection, ¢, (figs. 12 and 13,) and behind the process, f. 
Here they are connected with a bony tendon, to which the large 
muscles are attached which move the mandible. The mandibles 
have no appendages, and are very slightly connected at their base 
with the membranes of the buccal mass. When the buccal mass 
is separated from the body by force applied below, the mandibles 
invariably remain attached to their muscles. 
The remaining corneous organs at the extremity of the ateathe 
have been already described as connected with the lower mem- 
brane ; the two pairs m, 1, on the surface of this membrane, and 
the remaining, in its texture. The pair 1, have just been referred 
to as seen through the opening between the lips. 'These bones 
approximate at their apices; at the other extremity they curve 
backward and terminate under the junction of the two lips, (fig. 
13, and a a, fig. 12;) the bones, m, which are situated under 
the mandibles, are very finely pectinated on their outer margin ; 
they terminate at the same place with the preceding pair. 
The remaining bones form a kind of frame work for the lower 
membrane, ‘Three slender bones r, s, t, (fig. 17,) occupy the 
extremity of this membrane, and the bones, o, its inner portion. 
The bones, 0, extend backward and enlarge at the posterior part 
of the buccal mass, (g, fig. 17,) where they serve for the attach- 
ment of the muscles elevating the buccal mass. They appear to 
form by their union at their anterior extremity, (figs. 17 and 13,) 
a short, oblong process (k,) which is situated between the apices 
of the pectinated bones,m. The piece, n (figs. 13 and 17,) passes 
directly outward from this process, and is gradually lost in the 
membrane. 
This complicated apparatus, the buccal mass, appears to be 
composed of the upper and lower lips, united with the different 
parts of a pair of maxille 
We have often obgesued through the upper membranes of the 
buccal mass, and just in advance of the bony arch a, a, fig. 12, 
an obscure curved line nearly concentric with the anterior mar- 
gin of the buccal mass, (fig. 12,) which is frequently in motion. 
From the peculiarities of its action we suppose that there is here 
an internal opening to the esophagus. Within this inner mouth, 
Vou. XXXIV.—No. 2. 30 
