ANATOMY AND HISTOLOGY OF ZLIMAX AGRESTIS. 159 
ganglion is continued into the ‘circle of lobules’ 
(Liappchenkranz or Semper’s organ) in the form of several 
ganglionic nodules. A ganglion of homologous nature 
is also found in the Basommatophora, but they want 
the proper Semper’s organ. In the Prosobranchiata 
neither the subepithelial ganglion of the lips nor Semper’s 
organ is present.’’ The extract of Sochaczewer’s paper 
(52) says: ‘‘ Semper’s organ (or ‘lobate organ beneath the 
mouth-edge’) is not so richly supplied with nerves, as is 
stated by Semper, and it is more of a glandular nature.” 
Some time afterwards I found one specimen of Limaz 
maximus (8 inches in length, when fully stretched out), 
and in dissecting it I detected at last Semper’s organ, or 
the circle of lobules round the mouth-edge, as described 
by Sarasin. ‘Two spirit specimens apparently of the same 
species which I got about the same time, were not in such 
perfect condition as to allow of minute dissection. Fig. 2, 
Pl. XII., shows a dissection of the anterior part of the body 
of this species. The dorsal body wall has been taken away ; 
the tentacles, which were retracted into the body and 
were lying nearly parallel to the alimentary canal, have 
been cut through in the middle of their length, and the 
anterior portion of them has been bent forwards together 
with a small part of the skin of the head. Semper’s organ 
is seen to consist of five lobules forming a circle and 
surrounding the most anterior part of the buccal mass 
laterally and dorsally. There are two large lobules, one 
on each side, and three smaller ones placed dorsally. 
Nerves are easily seen going to the lobules, but it is 
difficult to tell by dissection alone whether the nerves end 
in Semper’s organ or simply pass through it to supply 
other organs. In transverse and longitudinal sections 
through the whole body of Limaz I ascertained that 
Semper’s organ consists of more or less pear-shaped cells 
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