1869.] The Treasures of Siluria. 29 



printer. Especially let us mention that M. Barrande's 'Systeme 

 Silurien du Centre de la Bolieme — Eecherclies Paleontologiques,' 

 Professor James Hall's ' Palaeontology of New York,' Mr. David- 

 son's ' British Silurian Brachiopoda,' Mr. Salter's numerous works 

 on Silurian fossils, and the Keports of the Canadian Geological 

 Survey, are the great storehouses from which Dr. Bigsby has 

 collected most of his material, while innumerable memoirs by an 

 army of English, Coutinental, and American authors have yielded 

 to his search an almost equal number of species. 



Dr. Bigsby has, indeed, spent a vast deal of time in groping 

 about amongst the archives of a host of ancient cemeteries of all 

 dates and of all climes. He has found records of the burial of 

 numerous groups of individuals, each group being known by a 

 distinct name. Some of these are represented in countries far 

 apart, and during successive periods of lengthened dm^ation ; but 

 the majority of them have remained true to their native country, 

 and have not survived the vicissitudes of climate and conditions to 

 which all regions are more or less subject. In other words, as we 

 shall have occasion to point out again, those individuaLs and com- 

 munities which emigrated to distant regions flourished and multi- 

 plied, after the manner of more modern emigrants, under the more 

 favourable conditions of their new habitation; while those which 

 remained true to their birthplace succumbed during a struggle for 

 existence with either their own progeny or new colonists, aggra- 

 vated by a decrease in the means of subsistence and a more 

 rigorous condition of external circumstances. 



The ' Thesaurus ' contains the names, dates, and habitations of 

 nearly nine thousand species, so far as they are at present known. 

 These species are classified zoologically into their respective orders, 

 the genera of each order and the species of each genus being then 

 given alphabetically. At the end of the list of members of each 

 order is given a " geographical summary," showing at a glance the 

 distribution of the genera and their species over the surface of the 

 globe. Finally, at the end of the book is a very complete list of 

 works on Silurian Palaeontology, which will necessarily be of great 

 assistance to future students of the subject. 



The untiring and long-sustained industry necessary to the 

 successful compilation of a work- of this kind is a quality possessed 

 by comparatively few men of science; and while we rejoice that 

 the Eoyal Society has recognized and rewarded the perseverance of 

 the author by a grant of 1001. in aid of the publication of his 

 book, we sincerely hope that the scientific public will follow so 

 distinguished an example, and will preserve the author from 

 pecuniary loss by purchasing a work of reference unique in its 

 aim, and without which every geological library must be regarded 

 as incomplete. 



