EXPLANATION OF PLATES. 349 



97. Mopalia sinuata Cpr. (intermediate valve). Pilsbrydel., 303 



98. Mopalia imporcata Cpr. (intermediate valve). Pilsbry 



del., .... 301: 



99. Mopalia muscosa var. hindsii Bd. Pilsbry del., . . 296 

 100. Mopalia muscosa var. hindsii Bd. Ross del., . . . 296 



PLATE 63. 



46. Mopalia muscosa Gld. (typical). U. S. Expl. Exped., . 295 



47, 48. Mopalia muscosa Gld. Ross del., .... 295 

 49-56. Mopalia muscosa Gld. Emerton del., . . . 295 



57. Mopalia muscosa var. hindsii Bd. Conch. Icon., . . 296 



58, 59. Mopalia lignosa Gld. Ross del., . . . .299 



60. Mopalia lignosa smooth form. Ross del., . . . 300 



61. Mopalia lignosa smooth form. Pilsbry del., . . . 300 



62. Mopalia lignosa (vespertina Gld.). U. S. Ex. Exped., . 300 



63. Mopalia insignis Newc. (=liguosa Gld.) 300 



PLATE 64. 



64-68. Mopalia ciliata Sowb. (Monterey Bay). Ross & 



Pilsbry del., 303 



69,70,71. Mopalia ciliata var. wosnessenkii Midd. Mai. Ross. 305 



72. Mopalia ciliata var. wosnessenskii Midd. Pilsbry del., . 305 



73. Mopalia ciliata var. wosnessenskii Midd. Ross del., . 305 

 , 74. Mopalia muscosa Gld. Emerton del., .... 295 



75. Mopalia acuta Cpr. Ross del., 297 



76-79. Mopalia acuta Cpr. (tail valves). Pilsbry del., . . 297 

 80, 81. Mopalia plumosa Cpr. (=acuta Cpr.). Foord del, . 298 

 82, 83. Mopalia lignosa form elevata. Ross del., . . . 300 



PLATE 65. 



73-75. Plaxiphora atlantica V. (tail valve). Pilsbry del., . 313 

 7H. Plaxiphora setiger King. Conch. Icon., . . .316 



77, 78, 79. Plaxiphora setiger King. Emerton & Ross del., 31 6 

 80-82. Plaxiphora egregia Ad. P. Z. S., ... 331 



PLATE 66. 



6, 7. Placiphorella velata Cpr. Emerton del., . . . 306 

 8-10. Placiphorella velata Cpr. (posterior valve). Pilsbry 



del., .... ..... 306 



11. Placiphorella velata Cpr. (intermediate valve). Pilsbry 



del., 306 



12. Placiphorella velata (Insertion-plate, seen from end of 



valve). Pilsbry del., 306 



13. Placiphorella velata (girdle-hair). Pilsbry del., . . 306 



14. Placiphorella borealis Pils. (intermed. valve). Pilsbrydel., 309 



