160 LIVERPOOL BIOLOGICAL SOCIETY. 
similar to those of the salivary gland. A duct was at first 
not visible. But that these glandular masses could not 
represent a sense-organ, as supposed by Semper, soon 
became evident, as the nerves which with the naked eye 
were seen going to them were with the microscope seen 
to pass through Semper’s organ without giving off any 
branches to it and finally end in the lips round the mouth. 
The exact relations of these nerves and of Semper’s organ, 
as seen in microscopical preparations, are as follows :— 
There is one median mass of lobules, placed posteriorly 
and a little dorsally to the lip, which protects the upper 
jaw; and there are two lateral masses of lobules, one on 
each side, posteriorly and a little dorsally to the two 
lateral lips. The nerves which pass through the lateral 
lobules spring from the supra-cesophageal ganglion, run 
along the buccal mass, and having penetrated the lobules, 
go to the lateral lips. Here they break up into the finest 
branches, and the fibres can be traced to the base of the 
epithelium. This epithelium covering the lateral lips, 
which are the same on both sides of the mouth, is formed 
of exceedingly high columnar cells, higher than in any 
other part of the body in Limax. Cilia are not present. 
As already mentioned, the dorsal lobules of Semper’s 
organ are smaller. The upper lip is provided with two 
very small nerves, which seem to spring from the buccal 
ganglia. The upper lip is also provided with high columnar 
epithelium, although the cells are here not so high as on 
the lateral hps. The cells of the upper lip nearer to the 
jaw are protected by a thin cuticle. A careful examination 
of longitudinal sections with a low power shows a narrow 
band of thin transparent tissue running from the lateral 
lobes of Semper’s organ to a papilla placed immediately 
above one of the lateral lips. With a high power it is 
seen that this transparent tissue consisted of bundles of 
