LYMNAIDEH OF NORTH AMERICA. 513 
glion of right side; 4, abdominal ganglion; 5, visceral ganglion of left side; 
6, pleural ganglion of left side; 7, pedal ganglia (separated and pulled away 
from their natural position); 8, buccal ganglia; 9, superior frontal nerve 
to labial region; 10, eye; 11, optic nerve; 12, nerve to right tentacle; 13, nerve 
to the neck; 14, nerve to penis-sac; 15, nerve to head of penis; 16, inferior cervi- 
cal nerve of right side; 17, large labial nerve; 18, superior cervical nerve; 19, 
inferior cervical nerve to left side; 20, lateral mantle nerve; 21, anterior mantle 
nerve; 22, aortic nerve; 23, sub-intestinal nerve; 24, right pallial nerve; 25, 
osphradium or organ of smell; 26, left, 27, right columellar nerve; 28, superior 
pedal nerve; 29, central pedal nerve; 30, inferior pedal nerve; 31, otocyst or 
auditory vesicle; 32, nerve to labial arteries; 33, anterior pellial nerve. 
PLATE VI. 
Figure A. Superior and lateral jaws of Lymnea stagnalis appressa Say. 1, 
superior jaw; 2, 2, right and left lateral jaws. 
B. Superior jaw of Lymnea stagnalis sanctemaric WALKER. 
C. Superior jaw of Pseudosuccinea columella (Say). 
D. Superior jaw of Radix auricularia (LINNE). 
E. Superior jaw of Bulimnea megasoma (Say). 
F. Superior jaw of Galba obrussa (Say). 
G. Superior jaw of Galba cubensis (Prr.). 
H. Superior jaw of Galba umbilicata (ADAMS). 
I. Superior jaw of Galba palustris (MULLER). 
J. Superior jaw of Galba emarginata (Say). 
K. Superior jaw of Galba catascopium (Say). 
L. Superior jaw of Galba caperata (Say). 
M. Superior jaw of Galba catascopium (SAy). Worn. 
N. Radula of Galba doddsi Baxer. 1, first lateral; 5, 7, 8, inter- 
mediate teeth; 9, 10, typical marginal teeth. 
O. Galba obrussa plica (LEA). Intermediate or seventh tooth of the 
radula. 
P. Radula of Galba hendersoni (BAKER). 9, intermediate tooth; 10, 11, 
lateral teeth. 
PLATE VII. 
RADULE. 
Figure A. Lymnea stagnalis appressa SAy. C, central tooth; 1, 2, lateral teeth; 
16, 19, lateral teeth with a second cusp above the ectocone; 
20, 21, intermediate teeth; 23, 32, 34, marginal teeth; 38, 44, 
outer marginal teeth. 
B. Pseudosuccinea columella (Say). C, central tooth; 1, first lateral; 
11, first intermediate; 13, 14, 15, 18, typical marginals; 27, 30, 
outer marginals. 
C. Radix auricularia (LINNE). C, central tooth; 1, first lateral (tri- 
cuspid) ; 2, 9, lateral teeth (bicuspid) ; 10, 11, 13, intermediate 
teeth; 15, 20, typical marginal teeth. 
D. Bulimnea megasoma (Say). C, central tooth; 1, first lateral; 2, sec- 
ond lateral; 6, modified lateral; 14, outer lateral; 17, intermedi- 
ate tooth; 18, 19, 21, marginal teeth. 
