ANATOMY AND HISTOLOGY OF LIMAX AGRESTIS. 157 
NERVOUS SYSTEM. 
The nerve collar of Lymneus palustris is known to 
consist of two supra-cesophageal, two pedal and five 
visceral (parieto-splanchnic) ganglia. One pair of the latter 
is connected laterally and posteriorly with the pedal 
ganglia and join ventrally and posteriorly the three other 
visceral ganglia. All the ganglia are most distinctly 
separated from each other, and therefore Lymneus is 
generally taken as the type for the nervous system of 
Pulmonata (see Lankester (5), Claus (1), Huxley (4), &c.). 
In Limax we find the same number of ganglia, but they 
are arranged in a different manner, the five visceral ganglia 
forming a row and being placed dorsally to the pedal 
ganglia. However the ganglia are fused together in such 
a manner that their number can be made out only in 
transverse sections. The relations between the different 
ganglia are easily understood by reference to fig. 1, Pl. 
XII., which represents a transverse section through the 
nerve-collar. Only the chief nerves are shown in that 
figure. 
Beddard (88) has described a glandular structure of 
unknown function placed above the supra-cesophageal 
commissure in Planorbis, and two such bodies placed above 
the two supra-cesophageal ganglia in Lymneus, and he 
refers to Liacaze-Duthiers (46), who had stated that this 
organ is present in all Pulmonata. I must say that I have 
not found it either in sections through the whole body of 
Limaz or in the sections through the isolated nerve-collar. 
As I have not made any special investigations on the 
other parts of the central nervous system of Limaz, I 
must refer to the extensive literature on this system, 
given at the end of this paper. 
Semper’s organ.—Now I pass on to discuss two organs 
