415 
of Gasteropodous Mollusca. 
The auditory capsule contains a single spherical otolithe, and 
is attached to the central ganglion at the root of the optic nerve. 
In Acteonia corrugata the auditory capsule is also furnished 
with a single otolithe. 
EXPLANATION OF PLATES XIX. and XX. 
Plate XIX. 
Fig. 1. Cenia Cocksii, much enlarged. 
— 2. Acteonia corrugata. 
— 3. Side view of the head of the same. 
— 4, 5, 6. Different views Lirnapontia nigra. 
— 7. Spawn of the same magnified. 
— 8. Larva of the same. 
— 9. A portion of one of the lateral hepatic trunks of Cenia Cocksii, show- 
ing its granular appearance. 
— 10. A few of the granules more highly magnified, exhibiting their mi- 
nute structure. 
Plate XX. 
Fig, 1. General view of the digestive system of Limapontia nigra : a, buccal 
mass ; h, tongue ; c, prehensile collar in advance of the same ; 
d, salivary gland; e, oesophagus; f stomach; gg g g, lateral he- 
patic trunks ; h, intestine ; i, anus ; j, cerebral ganglions. 
— 2. Tongue removed from the buccal mass : a, prehensile collar. 
— 3. Two joints or plates of the tongue more highly magnified. 
— 4. General view’ of the reproductive system : a, penis ; h, crystalline 
point of the same ; c, tube of the penis ; d d, testis ; e, duct of the 
same ; f junction of the duct of the testis with the bulb of the 
copulatory channel ; g, junction of the duct of the testis with the 
tube of the penis ; h h h, ovigerous sacs containing ova ; i, dilated 
portion of the oviduct ; j, junction of the oviduct with the tube of 
the penis ; k, mucous gland ; I, external orifice leading to the same, 
and through which the eggs pass ; m, two elongated glands pro- 
bably connected with the mucous gland ; n, shallow pouch at the 
external orifice leading to the spermatbeca ; o, copulatory cbannel ; 
p, bulb of tbe same ; q, spermatbeca ; r, duct of the same. 
— 5. Intromittent organ of Limapontia nigra: a, penis; h, crystalline 
point ; c, tube. 
— 6. Crystalline point (much magnified) of the penis of Cenia Cocksii, 
exhibiting the perforation at the extremity a. 
— 7. Profile view of the heart of Limapontia nigra : a, ventricle ; au- 
ricle; c, aorta ; d, venous trunk leading to the auricle ; e, dorsal 
skin ; //, clear space, probably showing the limits of a pericar- 
dium. 
— 8. Cerebral ganglions of L. nigra, with nerves : a a, central ganglions ; 
h, commissure uniting the same above tbe oesopbagus; cc, lateral 
ganglia ; d, buccal ganglia ; e e, eyes ; //, auditory capsules. 
— 9. Auditory capsule, with otolithe, more highly magnified. 
— 10. Eye greatly magnified, exhibiting the nerve, pigment cup, lens, 
cornea, and general capsule. 
