LTST OF ILLUSTRATIONS. xv 



22. External characters and minute structure of MonticuUpora {Hetero- 



trypa) Ulrichii, Nich., . . . . . .132 



23. Minute structure of J/tv///V/////>(;;7? (Hettroirypa) snbpi/lcheiIa,'^\c\-\., 135 



24. Tangential section of MonticuUpora [Heteroirypa) moniliformis, 



Nich., ........ 138 



25. ^xierndX c\\dixa.c\.ers oi Mo>iticiilipor a {Heterotrypa) James i, Nich., 144 



26. M.'\n\\X.Q sixMcXvixe oi MonticuUpora {Ileierot/ypa) Jamesi, l>[\ch.., . 145 



27. Tangential section o( MonticuUpora {Heterotrypa) implicata,'\]\x\ch, 148 



28. External characters and minute structure of MonticuUpora {Ilctero- 



t?-ypa) Trentofiensis, Nich., . . . . .150 



29. External characters and minute structure of MonticuUpora [Hetero- 



trypa) Girvanensis, Nich., . , . . .152 



30. External characters and minute structure of MonticuUpora {Diplo- 



trypa) pctropoUtana, Pand., . . . . .159 



31. External characters and minute structure of MonticuUpora {Diplo- 



t?ypa) IV/iiteavesii, Nich., . . . . .163 



32. External characters and minute structure of MonticuUpora [Mono- 



trypa) tmdulata, '^'ich.. (Trenton Limestone,) . . . 171 



T,'^. External characters and minute structure of MonticuUpora {Mono- 



trypa) undulata,'^\c\\. (Hudson River Group,) . . 173 



34. External characters and minute structure of MonticuUpora {Mono- 



try pa) Winteri, Nich., . . . . . .175 



35. External characters and minute structure of MonticuUpora {Mono- 



trypa) irregularis , Ulrich, . . . . .178 



36. External characters and minute structure of MonticuUpora {Mono- 



try pa) quad rata, Rominger, . . . . .181 



37. External characters and minute structure of MonticuUpora {Mono- 



trypa) clavacoidea, James, . . . . .184 



38. External characters of MonticuUpora {Monotrypa) pulchella, E. 



and H., ....... 188 



39. Minute structure of MonticuUpora {Monotrypa) pulcheUa, E. 



and H., ....... 189 



40. External characters and internal structure of MonticuUpora {Mono- 



trypa) petasif or mis, Nich., . . . . .191 



41. MAxmio. 'sXx\xc\.\xxt oi Moiiticulipora {Alonotrypa) pavonia,XyOx\)., . 197 



42. MonticuUpora {Prasopora) GraycE, Nich. and Eth, jun., . . 204 



43. Minute structure of MonticuUpora {Prasopora) Grayce, Nich. and 



Eth. jun., ....... 205 



44. External characters and minute structure of MonticuUpora {Praso- 



pora) SelwynU, Nich. (Trenton Limestone,) . . . 208 



45. External characters and minute structure of MonticuUpora {Praso- 



pora) Selzcynii, var. hospitalis, Nich. (Cincinnati Group.) . 210 



