64 MR. T. H. HUXLEY ON THE MORPHOLOGY OF THE CEPHALOUS MOLLUSCA. 
(3. Buccal ganglia or nerves. 
7 . Crystalline style. 
X. Its sheath. 
Accessory cartilages of the buccal mass. 
1 Tongue plate. 
Elastic plate. 
!«,. Muscles. 
PLATE II. 
Fig. 1. FiroloUes Desmarestii. (Magnified.) Male. 
Fig. 2 . FiroloUes Desmarestii. Female. Posterior extremity from the left side. 
Fig. 3. FiroloUes Desmarestii. Female. Posterior extremity from the right side. 
Fig. 4 . Penis of the male. 
Fig. 5. Egg-tube. 
Fig. 6 . Nervous system, with the termination of the pedal artery at y' . 
Fig. 7 . Cerebral ganglia from below. 
Fig. 8 . Right eye and tentacle. 
PLATE III. Atlanta Lesuerii. 
Fig. 1 . Animal in its shell (much magnified), from the right side. Male. 
Fig. 2 . The same from the left side, to show the arrangement of the nervous and 
vascular systems. 
Fig. 3. Post-abdomen, without the shell ; more enlarged, from the right side. 
Fig. 4 . Portion of the mantle-cavity and post-abdomen from the left side, to show 
the arrangement of the heart and branchiae. 
Fig. 5 . Portion of the penis. 
Fig. 6 . Cerebral ganglia, from the left side. 
PLATE IV. 
Fig. 1 . Pneu 7 uodermon ? A young specimen, to show the foim of the foot and its 
relations. 
Fig. 2. Euribia Gaudichaudii (Eydoux and Souleyet), from behind, placed, not as it 
swims, but so as to leave its parts in their normal position. This has been 
done with each of the figures in this Plate, except it be otherwise expressly 
mentioned. 
Fig. 3 . The head and foot of Euribia, seen from below. 
Fig. 4. Cleodora curvata (Eydoux and Souleyet), from the neural side. 
Fig. 5 . The same, from the haemal side. 
Fig. 6 . Cleodora aciculata, from the right side, without the shell. 
Fig. 7 . The same. The head and alae from the neural side. 
