APPENDIX. 11 



Page 23. 

 Line 19, for "Maudesly" read "Mundesly." 



Page 26. 

 Line 32, for " Terebratella pectita (Brong.)," read " Terebratula pectita (Brong.)." 



Page 27. 

 Line I, for " 1826 or 1827," read " 1816 or 1817," and erase the word "Terebratella." 



Page 51. 

 Line 10, for " Hornsey" read " Hamsey." 



PART III. 



OOLITIC AND LIASSIC SPECIES. 



Since the publication of this monograph (1851-2) very few additional species seem to have been 

 discovered; but certain points in connexion with those already described have received further elucidation. 



As we progress with the minute investigation, and collecting of species from each bed or layer, it always 

 becomes the more evident that we are still far from having attained a complete knowledge of the exact 

 period when certain forms first appeared, their duration, and the epoch at which they became extinct. 

 This most desirable and important knowledge cannot be obtained by a few excursions, nor in a short space 

 of time : it is the reward which will attend those indefatigable local geologists who, like Mr. Moore, 

 Dr. Wright, and others, assiduously explore every inch of the beds situated within the district they inhabit, 

 and who scrupulously assemble and correctly determine all the fossil contents of each bed in succession. 

 It is also of the utmost importance to examine, record, and illustrate the numberless variations due to age, 

 race, local condition, and malformation, presented by the individuals of each species, living congregated or 

 disseminated in the same bed and in different localities, that we may obtain a just clue to our appreciation of 

 the characters and limits to be assigned to our species, often too arbitrarily circumscribed. 1 



It is not difficult to say, for example, that the Terebratula ornithocephala, T. digona, T. obovata, and 

 other species of authors, are all referable to one species, and that most species are derivative of others ; such 



1 Mr. Woodward states that " some of the Brachiopoda appear to attain their full growth in a single 

 season, and all, probably, live many years after becoming adult. The growth of the valves takes place 

 chiefly at the margin : adult shells are more globular than the young, and aged specimens still more so. 

 The shell is also thickened by the deposit of internal layers, which sometimes entirely fill the beak and 

 every portion of the cavity of the interior which is not occupied by the animal, suggesting the notion that 

 the creature must have died from the plethoric exercise of the calcifying function converting its shell into 

 a mausoleum, like many of the Ascidian zoophytes." (' Manual of the Mollusca,' part ii, p. 213, 1854.) 



