INDEX. 239 
Marsh shells (family Paludinide), genera of, 53. 
Maizia heterodactyla, 208. 
Measurement of bivalve shells, 11. 
Methods of collecting and preserving bivalves, 19. 
Microscopic examination of, shells, 11, 12 ; cilia of bivalves, 
16; tongues of snails, 49; pulsations of the heart of 
Achatina, 172 ; development of pond snails, 182. 
Molluscous animals, 2; characters of, 2b. ; classes of, 3. 
Monomyary bivalves, 18. 
Mother-of-pearl, 12. 
Mouth of bivalves, 14. 
Muscular impressions in bivalve shells, 12. 
Muscular organs of bivalves, 17 ; gasteropods, 46. 
Mussels, 20 ; fresh-water, 25. 
Myvtitiv® (family), 20. 
Mytilus edulis, 20, 21, 28, 29. 
N. 
Nacreous layer of shell, 12. 
Nature of Zoological classification, 1. 
NeritTip# (family), 60. 
Neritina fluviatilis, 60; lingual ribbon of, 61; reproduc- 
tion of, 62. 
Nervous system of bivalves, 17 ; of water-breathing snails, 
52. 
O. 
Oxsect of Zoological classification, 7. 
Ocelli, 17. 
OncrpiAD (family), 89. 
Oncidium celticum, 89. 
Operculated land snails, 220. 
Operculum of shells, 46. 
Organs of sense of bivalves, 17 ; of water-breathing snails, 
52. 
Otina otis, 180. 
