INDEX. 
239 
Marsh shells (family Paludinidse), genera of, 53. 
Matzia 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, ib. ; 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. 
Mytilid^: (family), 20. 
Mytilus edulis, 20, 21, 28, 29. 
N. 
Nacreous layer of shell, 12. 
Nature of Zoological classification, 1. 
Neritidje (family), 60. 
Neritina fluviatilis, 60; lingual ribbon of, 61 ; reproduc¬ 
tion of, 62. 
Nervous system of bivalves, 17 ; of water-breathing snails, 
52. 
O. 
Object of Zoological classification, 7. 
Ocelli , 17. 
Oncidiad^e (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. 
