LIST OF ILLUSTEATIONS. XI. 



FIG. PAGE. 



53. Shell of Pleiirolomaria ..... 154 



54. A Pentacrinid . . . . . 1 58 



55. Skeleton of Northern Sea-Cow .... 168 



56. Leaf Butterfly ...... 178 



57. Test of Common Sea-Urchin .... 186 



58. Test of Secondary Sea-Urchin . . . 189 



59. Test of Paleozoic Sea-Urchin .... 190 



60. Test of Cretaceous Heart-Urchin . . 191 



61. A Nummulite -. . . . . . 197 



62. Flint Implement ... . 210 



63. Cone of Flint 212 



