DESCRIPTION OF PLATES. 
PLATE I. 
Galba reflexa (Say). Animal removed fron? shell, dissected, and the organs 
separated. 1, buccal sac; 2, cesophagus; 3, gizzard; 4, crop; 5, intestine; 6, 
pyloric portion of stomach; 7, rectum; 8, anus; 9, liver or digestive gland; 10, 
salivary gland; 11, ducts of salivary gland; 12, spire portion of body, containing 
one lobe of the digestive gland; 13, penis-sac; 14, vas deferens; 15, anterior 
protractor muscles of penis-sac; 16, posterior protractor muscles of penis-sac; 
17, penis; 18, retractor muscle of penis; 19, retractor of penis-sac; 20, penial 
opening; 21, vaginal opening; 22, duct of receptaculum seminis; 23, receptaculum 
seminis; 24, first accessory albuminiparous gland; 25, second accessory albumin- 
iparious gland; 26, oviduct; 27, uterine portion of oviduct; 28, albuminiparous 
gland; 29, posterior portion of prostate; 30, anterior enlarged portion of pros- 
tate; 31, prostatic portion of vas deferens; 32, ovisperm duct; 33, ovotestis; 
34, ventricle; 35, auricle; 36, pericardiac cavity; 37, pulmonary vein; 38, plexus 
of blood vessels on left lobe of kidney; 39, pulmonary sac or rete; 40, glandular 
portion of kidney, or renal organ; 41, ureter; 42, cut edge of muscles connect- 
ing head with velum; 43, velum; 44, muscular collar of velum; 45, cut edge of 
head; 46, tentacle; 47, supra-esophageal ganglia; 48, nerve to head or penis; 
49, nerve to penis-sac; 50, nerve of female-genital organs; 51, columella muscles 
and foot retractor muscles; 52, right retractor muscle of buccal sac. 
PLATE I. 
Figure A. Shell of Lymnea, to illustrate different parts. Much enlarged. 1, 
spire; 2, aperture; 3, body whorl; 4, suture; 5, parietal wall; 
6, columella or inner lip; 7, peristome or edge of outer lip; 
8, umbilical chink; 9, sculpture of growth lines and spiral lines 
producing the characteristic decussated appearance of the sur- 
face. 
B. Young Lymnea just previous to its escape from the egg. 
C. Trochosphere stage of Lymnea stagnalis LINNE. 1, mouth; 2, velum. 
(After Lankester.) 
D. Veliger stage of Lymnaea stagnalis Linne. 1, mouth; 2, velum; 3, 
foot; 4, tentacle; 5, eye; 6, shell (after Lankester). 
PLATE, iii. 
All figures are greatly magnified. 
Figure A. One-half complete row of teeth of Galba reflera (Say); ¢, central 
tooth; 1-12, lateral teeth; 13-15, transition teeth; 16-33, marginal 
teeth. X 300. . 
B. Teeth of Lymnea stagnalis LINNE, to show position of central tooth 
in relation to lateral teeth. The first lateral to the left and the 
first three laterals to the right are shown. Also, the two rows 
and the median cusp of a third row. X 516. 
C. Lateral tooth of Lymne@a showing named parts. 1, base of attach- 
: ment; 2, reflection; 3, cutting portion of tooth; 4, entocone or 
