232 Description of a Species of Caligus. 
The lateral and anterior margin of the buccal mass is formed 
by aslender bone, (c b, fig. 12,) which forms a projection posteri- 
orly where it suddenly curves around inward, and runs backward 
a short distance nearly parallel with the margin. These bones 
form the sides to the lower membrane of the cavity of the mouth, 
At the anterior extremity of the buccal mass within, they are 
connected with several small bones which run to the medial line 
of the mouth, and constitute part of its manducatory apparatus, 
(m, 1, and n, fig. 13, r, s, t, fig. 17, an under view ;) these bones 
lie either on or in the lower membrane of the mouth. No portion 
of the wpper membrane of the buccal mass is connected with the 
bones of the lateral margin except a small subtriangular piece 
near the anterior angle, (dae, fig. 12.) 'These pieces leave be- 
tween them and the anterior margin of the buccal mass a semi- 
eircular opening ; the edges of this opening are furnished with 
cilie, and constitute the lower margin of the lunar opening, or 
the lower lip. This lower lip is divided at its centre, (b, fig- 12,) 
and the edges thus formed are curved inward, so that in a vertical 
view several ciliz are projected together, and have the appearance 
of one branching cilia. 
_ The whole membrane. forming the upper portion of the buccal 
mass may be called the upper lip. It is represented separate in 
fig. 15. It is united with the lower portions, at its posterior eX- 
tremity, (pp, figs. 12 and 15.) It may be viewed as consisting 
of two parts, an anterior movable, and a posterior, apparently 
immovable. The movable portion, which is very much the 
smallest, is an elliptical, nearly circular, membrane, inserted in @ 
semicircular concavity (aa) in the anterior margin of the immova- 
ble portion. Its front edge is coarsely subcrenated and furnished 
with ciliz. The large immovable portion of the upper lip is 
bounded by a bony edge, on all sides except posteriorly. At f, 
(figs. 12, 15,) there is a curved process elongated outward, serv- 
ing for the attachment of a muscle. 
Through the opening between the lips, (fig. 12,) we may ob- 
serve the two slender bones l, (fig. 13,) and just within these, there 
are visible, through the membranes, two dentated organs, which, 
when the membranes above are removed, appear as represented 
in fig. 14. These organs are the mandibles. They are long 
slender organs with.a falciform termination, curved inward 
Senced mc. Sntetion:elgns. tha number of teeth is about 
