ERRATA. 
Page 12, line 18, for Ulkich read Nicholson. 
Page 16, line 1!, for n. s. g., read Hall. 1886. 
Page 40, lines 6 and 7 from bottom, for Rhinodictya read Rhinidictya. 
Page 41, line 15, for Rhinodictya read Rhinidictya. 
Page 74, lines 2 and 3, for 5, 6, read 6, 7. 
Page 83, line 15, for figs. 30-32, read figs. 30-33. 
Page 84, line 9 from bottom, for 26 read 27. 
Page 96, lines 7 and 9, for 37, 38, read 36, 37. 
Page 103, line 21, for 7, 8, read 7-10. 
Page 106, the name Fenestella pertenuis was given to a Niagara species in 1879, and the present species 
is named Fenestella Proutana by S. A. Miller, and the name should have been adopted in this volume. 
Page 110, line 4 from bottom, for 22, 24, read 22-24. 
Page 120, line 4 from bottom, Fenestella (Reteporina) coalescens is a new species. 
Page 156, line 2, insert plate xliii, fig. 1. 
Page 178, line 7 from bottom, for fig. 6, read fig. 2 
Page 179, line 2, for fig. S, read fig. 9. 
Page 182, line 18, for Erie county, read Genesee county. 
Page 189, line 1 from bottom, for Erie county, read Genesee county. 
Page 193, line 3, Nbmataxis simplex is a new species. 
Page 193, line 9 from bottom, for Erie county, read Genesee county. 
Page 194, line 14, for Erie county, read Genesee county. 
Page 215, line 5 from bottom, for 22, read 20. 
Page 239, line 9, Coscinella elegantula is a new species. 
Page 243, line 16, for Erie county, read Genesee county. 
Page 245, line 1, Stictopora rectalinea is a new*pecies. 
Page 246, line 1, Stictopora tumulosa is a new species. 
Page 249, line 9 from bottom, for .15 to .25 mm., read 15 to 25 mm. 
Page 266, line 8, Prismopora lata is a new species. 
Page 283, line 17, for 1849, read 1844. 
Explanation of plate xxiv under Receptaculites inedndibuliformis for page 289, read page 290 ; under 
Ischadites squamifer, for page 290, read pag-e291; under Ischadites bursiformis, for page 290, read page 291. 
