CONTENTS. 



Xlll 



Page 



57. Nucula - - - 97 



58. Trigonia - - - - 97 



Family XL — Naiidce - - 98 



59. Unio - - - - 100 



60. Hyria - - - - 101 



61. Anodonta - - - - 101 



62. Iridina - - - - 102 



Division IV. — Conchifera ambigua - - 103 



Family XII. — Chamidce - - - 103 



63. Diceras - - - - 103 



64. Chama - - - - 104 



65. Etheria - - - - 105 



Order III.— Monomyaria - 106 



Division I. — Ligament long and marginal - 107 



Family I. — Tridacnidce 



- 107 



66. Tridacna 



- 107 



67. Hippopus 



- 109 



Family II. — Mytilidce 



- 109 



68. Modiola 



- 110 



69. Lithodomus ~ 



- 110 



70. Mytilus 



- Ill 



71. Pinna 



- 112 



Family III. — Malleidce 



- 114 



72. Crenatula 



- 114 



73. Perna 



- 115 



74. Malleus 



- 116 



75. Vulsella 



- 117 



76. Avicula 



- 118 



