116 THE GASTROPODA 
especially in the Pulmonata, in which group the pleural ganglia 
scarcely ever give off any nerves. In all the Euthyneura except 
Actacon (Fig. 57), Chilina, and Lata (Fig. 96) the infra-intestinal 
ganglion is fused with the abdominal (Fig. 97, ab) in sach a manner 
that the latter appears to participate in the innervation of the 
mantle—for instance, in the innervation of the inferior pallial lobe 
and the pallial branchia of the Planorbidae—and the pallial nerves 
issuing from the left moiety of the visceral commissure originate 
from a special and newly-developed ganglion, viz. the parietal 
ganglion of the Pulmonata (Figs. 96, g.pa; 97, sp). As regards the 
viscera, the heart, the kidneys, and the gonad receive their essential 
nerve supply from the abdominal ganglion, the alimentary canal 
receives its nerves from the stomato-gastric centres, and these latter 
nerves sometimes exhibit accessory ganglia on specialised parts of 
the alimentary tract, such as the gizzard of Tectibranchia, ete. 
5. Sense Organs.—In addition to sensory cells scattered over the 
whole surface of the body, Gastropods possess special sensory 
organs usually designated by the names rhinophore, osphradium, 
otocyst, and eye. While the whole surface of the integument is 
sensitive, tactile sensibility is more particularly localised in the 
anterior regions of the body: in the head, in the margin of the 
foot (in marine Streptoneura the whole ventral surface of the foot 
exhibits a fine nervous network), and in the regions of the body 
specialised to form tactile appendages of various shape and situa- 
tion. Such are the cephalic tentacles—especially the anterior pair 
in quadritentaculate Euthyneura; the labial palps (Fig. 117, te”), 
which bear a row of tubercles in some Pulmonates; the pedal 
tentacles of Vermetus (Fig. 45, p.t); the epipodial tentacles of the 
Rhipidoglossa (Fig. 130, XI), 
i which have ciliated sensory 
“fe Nea organs at their bases; and 
the pallial appendages, such 
as the dorsal papillae of the 
Nudibranchs. 
The Rhinophores, or olfac- 
tory organs, as they are called, 
Fic. 98. are likewise constituted by 
Bulla (Haminea) navieula, right-side view. c.h, the cephalic tentacles, especi- 
cephalic hood; e, eye; f, foot; k.o, hermaphrodite : Bac 
orifice; il, inferior pallial lobe; m, mouth; m.o, ally by the posterior pair in 
unmnal groove sh shell. (After Guiart) the quadritentaculate Euthy- 
neura. The whole surface of 
these tentacles is covered by little ciliated papillae, giving them a 
silky appearance, in many khipidoglossa, ¢.g. Scissurella, Haliotis, 
Trochus, Gena, Molleria, Cyclostrema, Neritina, in Caecum (Fig. 68, te), 
ete. The olfactory nerve divides into many ramifications which end 
on the surface of the tentacle in olfactory sensorial cells. In many 
