AND HABITS OP MARINE TESTACEOUS MOLLUSCA. 
505 
the pharynx from its attachments as far as the upper jaw, we shall have ex- 
posed the parts as in fig - . 10. 
In this figure we observe a muscular apparatus in the pharynx similar to 
that of Turbo, each columnar muscle having a valvular appendage connected 
with it, which appears to close the opening. The active portion of the tongue 
is seen on the part which the pharynx had covered, and surrounding this part 
is an irregular edge, representing the loose membrane from which the pharynx 
had been separated, and which, acquiring a firmer attachment as it recedes, is 
at length blended with the muscles. The accessory cartilages cause the breadth 
of the jaws in front, and the posterior cartilages are marked by the rounded 
projections between which the tongue descends. None of the muscles can be 
distinctly displayed in this view. 
Raising the whole mass, a number of small muscles are seen passing for- 
ward from the extremity of the jaws to the floor of the cavity, and forming 
two series ; the first, inserted across the middle of the cavity ; the second, 
which appears as a single broad muscle, a little within the mouth. The whole 
are to be removed, and the jaws may be detached altogether. 
A pair of very thin muscles (e, fig. 13.) may now be traced passing from the 
posterior extremities over the accessory cartilages to the wings of the upper 
jaw, which they raise. Underneath appears a broad straight muscle, whose fibres, 
as it advances towards the mouth, separate to either side, exposing a yellow- 
looking mass, which might be mistaken for a gland, but which is an extension 
of the soft lips forming a considerable cavity. Within this cavity are found 
the extremity of the tongue, and a small conical papilla, striated transversely, 
which terminates the lingual membrane, and which is probably the organ of 
taste, as I observe it to be constantly thrown forward in the act of feeding. 
The cavity is to be laid open ; and the muscles being divided and turned aside, 
the parts will appear as in fig. 1 1. 
All the principal muscles are now exposed. Those which have been turned 
aside (d, d) are inserted into the wings of the upper jaw, which they depress 
and retract. The narrow straight muscles (/,/) arising from the extremity 
of the posterior cartilages, pass on beneath the cavity of the mouth to the ex- 
tremity of the lingual membrane. Near the insertion of these muscles their 
outermost fibres separate, and pass to the attachment of the pharynx, behind 
