ERRATA IN THE REFERENCES TO THE PLATES. 
*** The volume having been printed some time before the plates were engraved,. and even while 
many of the figures were still to be delineated, several discrepancies occurred in the references, which 
will be found rectified in the descriptions accompanying the plates. 
Page 6. PI. iii, fig. 3, should be PI. ii, fig. 3; and PI. ii, fig. 1, should be PI. iii, fig. 1. 
10. PI. iv a should be PI. iv (bis). 
11, Modiolopsis primigenius should refer to PI. iv (bis), fig. 2. 
20. PI. v (bis) should be PI. v a. 
24. PI. ix, the fig. 1 a, b, c, should be fig. 1, 2, 3; and fig. 2, same plate, page 25, should be fig, 4. 
66. PI. xxii, the fig. 2 should be fig. 3, and fig. 3 should be fig. 2. 
125 & 126. PI. xxxiv a should be PI. xxxiv (bis). 
129. PI. xxxv should be PI. xxxv (bis). 
136. Stromatopora concentrica should refer also to PI. xxxvii a, fig. 1. 
171. Lichenalia concentrica should refer also to PI. xxxvii a, fig. 2. 
187. PI. xli, the fig. 3 should be fig, 4 V 
281. PI. Ivii should be PI. lviii. 
300. PI. lxvi should be PI. A lxvi. 
350. PI. lxxxiv should be PI. lxxxiii. 
