The Morphology of a Solenogastre. Dat 
most important fact that the labial ganglia are connected with a 
typical subradular system. 
Comparing this part of the nervous system with what exists in 
the chitons it will be seen that the so called sub-cerebral portion 
of the oesophageal ring behaves exactly as the labial system of 
prosobranchs. It is connected with the buccal nerves which form 
a complete ring about the pharynx above the radula sac and with 
the subradular ganglia. These relations have been described 
heretofore (PLATE, 1901) and are readily determined from an 
examination of the accompanying figures. 
Nr 
Anterior portion of nervous system somewhat diagrammatic, of (1) prosobranch, 
(2) solenogastre and (3) chiton. cg cerebral ganglion; de dorsal buccal commissure; 
Ig lateral nerve cord; sr subradular ganglia; vc ventral buccal commissure. The 
labial system is in heavy black. 
Fig. A. 
In the solenogastres the centralization of the ganglion cells has 
resulted in the formation of relatively long connectives to the pedal 
and lateral ganglia and in bringing the cerebral nerve masses close 
together upon the dorsal side of the digestive tube. Nevertheless 
the relations of what I consider to be the labio-buccal system have 
not been disturbed and exhibit a close similarity to the foregoing 
groups.!) Im both species of solenogastres which I have studied 
(Proneomenia hawaiiensis and Rhopalomenia scandens) the labial 
connectives are of relatively great length, especially in the genus 
1) In a paper on the subradular organs of solenogastres (1904) I 
believed that the nerve supply of these bodies originated in the buccal 
system and finding a commissure dorsal to the radula considered that the 
other fibres from the labial ganglia innervated the wall of the gut. A 
renewed study of sections shows that there is a true labial commissure 
which is described in the body of the text. 
