500 
MR. OSLER’S OBSERVATIONS ON THE ANATOMY 
all the muscles already described ; and the insertion of the retractors of the 
tongue will be seen, as in fig-. 3, by dividing- the ligament which unites the 
jaws. There are, in addition, a small muscle (f 3 fig. 3.) passing forward from 
the tongue to be inserted into the floor of the cavity on the right side ; a pair 
of delicate muscles, not figured, which arise from the posterior part of the 
jaws, and pass forward over the lateral muscles to be inserted near the sides 
of the mouth ; and a very small one (g, fig. 1. and 3.) which occupies a hollow 
near the point of the jaws, and assists in expanding them. 
The stomach may now be turned forward, detached from the jaws, and 
opened longitudinally on the under part. The contained oesophagus, the lips, 
with a pair of very small internal lips between them, and the valves in front, 
will then be seen, in a favourable specimen, as in the figure. 
The nervous system, which in some of the mollusca embarrasses the dissec- 
tion from its size, is here very inconsiderable : indeed, it is only by a very 
careful examination that it can be discovered. A pair of very small ganglia 
at the base of the tentaculse are connected by a cord which crosses the fore part 
of the stomach. A filament surrounds the attachment of the stomach to the 
jaws, and another runs along the left side to the back of the same organ, 
which it nearly crosses. The whole will be displayed by carefully detach- 
ing the integuments from above ; but this is a task of extreme difficulty, 
for the stomach is almost of a pulpy texture, and tears with the slightest 
force. 
In Turbo littoreus , the parts are far more simple than in Trochus ; and the 
dissection, notwithstanding their very small size, is attended with fewer diffi- 
culties. The body being cleared from the spire and mantle, the integuments 
are to be completely cut away, as in fig. 5, leaving the contained parts in their 
natural situation upon the muscle of the spire. The fleshy mass connected 
with the mouth, which in the largest specimen scarcely exceeds the size of a 
hemp-seed, will then be seen in front, with the oesophagus cresting it, and run- 
ning back to its termination in an elongated stomach. The extremity of the 
tongue, wound into a compact spiral, rests upon the stomach ; while the sali- 
vary glands, a soft, yellow, granular substance, occupy the space between the 
spiral and the mass of the mouth. All these parts are to be distinguished 
through the integuments. The chief caution to be observed in this stage of 
