V,) 
of the heart and the reproductive apparatus can with a great de- 
gree of probability be traced to branches from the lateral nerves; 
as also can the nerve running towards the apparently sensory infun- 
dibulum on the posterior extremity (see p.9). The pre-anal gland 
on the contrary (see p. 16) in the prolongation of the foot-gland, 
is innervated from the pedal nerves, close to their posterior com- 
missure, as are also the foot, foot-gland and adjoining tissues. It 
especially deserves note however, that close to the posterior extrem- 
ity of the animal I find rather considerable nervebranches directed 
dorsally and apparently running to the museular investment of the 
rectum, which take their origin from the longitudinal pedal nerves. 
A rather considerable number of nerves in the posterior extremity 
of the animal behind the reetum and anal cavity, originating from 
the lateral nerves, suggest the hypothesis that they are partly 
remnants of a former arrangement since lost, in which they 
served towards the innervation of branchiae that then came to 
their full development in this very region, as they do in the close- 
ly allied genera Neomenia and Chaetoderma. 
The facts above described will no doubt justify the conelusion 
that the condition of the nervous system in Proneomenia may prove 
a subject for fruitful speculation. The amount of deviation from 
the Molluscan typical nerve-system present in the Chitonidae which 
induced v. IHERING to remove his Amphineura from the Mollusca 
and which was afterwards again studied and better interpreted by 
SPENGEL (30), is even greater in the other order of the Amphi- 
neura. The nervous system of Proneomenia presents more points 
of comparison with lower types than does that of the Chitons and 
thus the line may perhaps be followed up by which the specia- 
lized forms of the nerve-system in the more differentiated classes of 
Mollusks are linked not only to that of the archaic class ofthe Am- 
phineura but through these to that of more primitive ancestors, 
still lower down amongst the simpler types of invertebrates. 
Elsewhere I have described (9) what appeared to me a very 
primitive stage of the nervous system, in which, although a cepha- 
