542 W. A. HERDMAN AND J. A. CLUBB. 
the so-called ‘‘ epipodia” of molluscs are not in all cases of the 
same nature ; and that the epipodia of (e.g.) Aplysia and of 
the Pteropods are the edges of the ventral surface of the foot 
proper, and are, therefore, not really homologous structures 
with the epipodial processes of an ordinary rhipidoglossate 
Gastropod, such as Trochus, as they are not outgrowths from 
an “ epipodial line” extending from the region of the tentacles 
on the back of the head along the sides of the body posteriorly 
and supplied with nerves from the pedal ganglia, as it was 
originally defined by Huxley.! For such independent struc- 
tures (as in Pteropods and Aplysia) Pelseneer suggests that 
the name ‘‘ parapodia” given by von Jhering should be em- 
ployed. We have already protested against the use of this 
term in a new sense, and Garstang has, therefore, proposed 
lately the substitute ‘‘ pleuropodia” to indicate such dorso- 
lateral projections as those of Aplysia and many other 
Opisthobranchiata (including the cerata of Nudibranchs) which 
have had doubt thrown upon their epipodial nature. 
On the other hand, Lacaze-Duthiers and others of his school 
have lately regarded the epipodia as pallial outgrowths inner- 
vated from the pleural ganglia; but Pelseneer has conclusively 
shown that, in Trochus and other Rhipidoglossa at least, the 
processes in question are supplied by epipodial nerves which arise 
from the dorsal part of the pedal ganglia, or the pedal ganglionic 
cords, or at the anterior end from the cerebro-pedal connectives, 
and that therefore they are entirely pedal in their nature.” 
Consequently it has seemed to us of importance to deter- 
mine the nerve-supply to the cerata in several different types of 
Nudibranchiata, with the view of settling whether or not these 
1 «Phil. Trans.,’ 1853, pp. 40, 47, &e. 
2 In a third note (‘ Bull. Scient.,’ t. xxiii, p. 437), issued August 18th, 
1891, and which reached us some time after this paper had been written, and 
read at the British Association meeting, Pelseneer not only distinguishes 
between the ‘“‘epipodia” and ‘ pleuropodia,” as explained above, but also 
separates off from both the cerata of Nudibranchs, as being “ processes of 
the dorsal integument always innervated by the pleural ganglia.” This is not 
in accordance with the facts as demonstrated by our observations detailed in 
the following pages, 
