PRELIMINARY REMARKS. 9 



omitted, among my references, to allude to authors who have furnished simple lists or 

 catalogues of species, because, having no means of ascertaining that these iden- 

 tifications are correct, it would be merely burdening the list of references to no useful 

 purpose. 



It now remains for me to express my warmest thanks to those numerous friends who 

 have so zealously assisted me, and who have contributed so largely to the success of the 

 present work by the loan of specimens, and by the advice they have afforded. 



To Professor Owen, Mr. Waterhouse, Mr. Woodward, Dr. Gray, and Dr. Baird, for 

 the use of the specimens in the British Museum, wherein so many of Professor Phillips's 

 original figured types are preserved. To Sir R. Murchison and Professor Huxley for the 

 liberal assistance and communication of specimens contained in the Museum of Practical 

 Geology, or Geological Survey ; to Mr. Salter and Mr. Baily, of the same institution, for 

 much valued help and useful information. To the Council of the Geological Society, 

 for the kind manner in which they placed the valuable collection of Carboniferous species, 

 forming part of the Society's Museum, at my disposal, for the use of the present work. 

 To Mr. Bowerbank, for all the trouble he has taken relating to this monograph. To 

 Professor Tennant, Mr. Rupert Jones, and Mr. Morris, of London, I am indebted for the 

 loan of many specimens, but in particular to Mr. J. de C. Sowerby, who, in the most 

 liberal manner, gave me the unlimited loan and use of the original specimens described 

 by his father and himself in the ' Mineral Conchology.' 



To Professor Sedgwick, for the obliging manner in which he has allowed me free access 

 and use of the specimens in the Cambridge University Museum, and in which are assembled 

 a large proportion of Professor M'Coy's named and original types. Also to Professor 

 M'Coy, Mr. Carter, and L. Barrett, who at various times have kindly assisted in my 

 researches while at Cambridge. 



To Professor Phillips, of Oxford, for the loan of his private collection, containing many 

 of the original examples, published in the ' Geology of Yorkshire,' as well as for the kind 

 advice and interest he has taken in the success of the present monograph. To Mr. 

 Etheridge, and the directors of the Bristol Institution Museum for the use of their speci- 

 mens, as well as to Mr. Charlesworth, and the directors of the York Museum. 



To the Earl of Ducie, Dr. Wright, of Cheltenham, Messrs. Walton and Moore, 

 of Bath ; Mr. Parker, Mr. Binney, and Mr. Ormerod, of Manchester ; Mr. Reed, of York, 

 Mr. Howse, of South Shields, Mr. Tate, of Alnwick, Mr. Muschen, of Birmingham, 

 and the Rev. J. G. Cumming, of Lichfield (formerly of the Isle of Man), for the loan and 

 gift of many specimens, as well as for much valued information connected with the species 

 from their respective districts, or collections. I must, however, here tender my especial 

 and warmest thanks to my valued friend, Mr. Edward Wood, of Richmond (Yorkshire), 

 for the indefatigable and zealous exertions he has displayed in assembling material 

 and information of various kinds; to his kind and liberal assistance this monograph 



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