AND HABITS OF MARINE TESTACEOUS MOLLUSCA. 
503 
It is not to be questioned that Patella vulgata has considerable power of 
locomotion. I have taken one from the side of a recently stranded wreck, 
some feet above the beach ; but it is certain that it often remains for life on 
the same spot. Large specimens are always to be found adhering to an irre- 
gular and naked rock, with their shells distorted in exact correspondence with 
all its inequalities. In such situations they necessarily depend for their food 
upon the fragments floating in the water ; and on the rocky shores where they 
are found they will derive an abundant supply from this source. The little 
eddy which plays around them from the motion of the tides and waves, will, 
when the shell is raised from the rock, bring any floating fragments within 
reach of the lips. 
Patella gorges its food entire. This fact might have been inferred from its 
anatomy, and it is proved by observation. Some time since, Mr. Dillwyn and 
myself, dissecting some specimens, found in the stomach of one of them a por- 
tion of a fucus so large, that he was enabled at once to recognise it as F. pin- 
natifidus ; and in a recent communication he informs me that he has found 
fragments of Ulva linza in the stomachs of others. It is not however to be 
supposed that Patella never feeds upon growing marine plants : indeed I have 
seen it in the act of preying upon the soft dark substance so often found cover- 
ing the shell of Trochus umbilicatus. 
The jaws of Patella are furnished with a skeleton far less simple than that 
of Trochus. A pair of triangular cartilages, which I shall call the “ lateral 
jaws,” are united by a ligament along their base to the point, and each has a 
smaller “ posterior cartilage ” articulated with its extremity. A pair of “ acces- 
sory cartilages” of the size and shape of linseed, rest, with their thicker extre- 
mities forward, on the outside of the lateral jaws. Corresponding with the 
centre of these, within the jaws, arise a pair of elastic and pyriform bodies, 
which sink between the expanded jaws, and rise above them when closed. In 
addition to this apparatus, there is a bony upper jaw, formed of a central por- 
tion, whose figure is the vertical section of a hollow cone, with a pair of broad 
processes like wings given off from its sides ; and with a distinct and mode- 
rately broad margin, whose extremities are free, surrounding the base. The 
muscles of the pharynx arise from the superior edge of the upper jaw, and the 
active portion of the tongue corresponds with its concavity. 
3 t 2 
