ERRATA.— Continued. 



Page 213, line 1 For sentence beginning "on the other hand," 

 read " on the one hand, there must be taken 

 into account the changing and constantly- 

 lessening divergence of pencils of large aper- 

 tures after entering the objective : on the other 

 hand, the opposite condition, &c." 



216, ... 17. For "in," read "on." 



217, ... 4. For " two first," read " first two." 



217, ... 21. For "every improvement," read "every later 



improvement," and cancel "since," 



218,... 7. For "affected," read "effected." 



219, ... 27. For " as," read " and." 



221,... 16. For " in the," read " IX. In the." 



222, ... In note, two lines from bottom, for "Roberts'" 



read " Nobert's." 



228, ... 9. For " refracted," read " refrangible." 



229, ... 28. For "thing," read "things." 



230, ... 12. For "So long as the angle, &c." read " As long 



as the size of aperture remains so large that, 

 &c." 



230, ... 29. For " definite kind," read " prescribed form." 



231, ... 8. For " illuminations," read "illumination." 



234, ... 19. For " surface," read " surfaces." 



240, ... 11. For " alteration," read " alternation." 



255, ... 18. Cancel "does." 



246, ... 27. For " content," read " contents." 



250, ... 1. For "opeivation," read "observation." 



251, ... 18. For " From the point, &c." read "XXIII. From 



the point, &c." 



253, ... 2. For "content," read "contents." 



253, ... 6. For "in," read "or." 



254, ... 20. For " objective," read "objectives." 



255, ... 32. For "pencil," read "pencils." 



. ... 255, ... 34. For '• condition," read "conditions." 



260, ... 11. For " partially," read " potentially." 



261, ... 23. For " condensors," read " condensers." 



264, ... 8. For " sound," read " sand." 



266, ... 7 from bottom. For " Holapella," read " Holopella.*' 



271, ... 8. For " Limestone," read "sandstone." 



277, ... 14. For " Palmobranchiata," read " Pulmobran- 



CHIATA." 



301, ... 14. Fox '^ ^Icistes" XQdLdL ^^ JEcistes." 



304, ... 5 lines from bottom. For '' Fontanalis," read *^Fon^ 



tinalis " 

 306. ... 10 from bottom. For '•'■ amygdalima^' read ^'atnyg^ 



dalina.'' 



309, ... 9. Ylv " albipiwta," Tea.6. " albtpun'-ta." 



189, ... column 1, line 12 from base. For " Terebratuta," read 



" Terebratula. " 



319, ... column 1, line 12. For " crinisria," read "crinistria." 



322, ... column 2, line 1 2. For " covonata," read " coronata." 



column 2, line 9 from base. For "oralis," read "ovalis." 



333, ... column 2, line 7 from base. For " canalienlata," read 



" canaliculata." 

 ...... 338, ... 9. For "seam," read " seams." 



i 348, ... 7. For " centnry," read " century." 



