1867.] ' Thesaurus Siluricus.' 373 



the present Palaeontologist to the Institution over which Sir Roderick 

 presides. 



To the careful superintendence of these two eminent naturalists I am 

 indebted for corrections and suggestions of the greatest importance, and 

 particularly as relates to Britain and to Europe generally. 



My matter has been principally found in the voluminous and truly 

 priceless writings of Murchison, Sedgwick, Barrande, Sowerby, DeVerneuil, 

 James Hall, M'^Coy, Salter, Billings, Angelin, Eichwald, Shumard, and 

 Davidson — together with those of other authors, some of whom are scarcely 

 of inferior merit*. 



I have been favoured with many unpublished contributions from my 

 friends Mr. Billings (the learned Palaeontologist of the Canadian Survey) 

 and Principal Dawson, F.R.S., of M'^Gill College, Montreal, — also, through 

 the kindness of Mr. Salter, from the Himalayas (Colonel Strachey, B.E.), 

 from West Tasmania (Dr. Milhgan), from South Wales (Henry Hicks, 

 Esq.)> and from the late Mr. Wyatt-Edgell. 



I propose to give to this effort the name of " Thesaurus Siluricus." 

 Besides its use for general reference in the closet and in the quarry, the 

 * Thesaurus ' provides a high station from which the student may obtain a 

 broad survey of the Silurian populations of the whole earth. It will 

 assist in tracing the extent, shape, and varying depths of areas, in dis- 

 covering regional affinities, differences, and those great zoological seve- 

 rances which we call breaks. By its aid we may compare horizons 

 remote from each other, and, moreover, note the frequent changes of 

 many kinds which take place while the epoch is working out its long 

 history. It will place under our examination numberless communities of 

 life, their constituents, habits, rise, and decline. 



The * Thesaurus' points to the universahty (as defined) at times proximate 

 everywhere, brings into prominence the riches, magnitude, and wide diffu- 

 sion of the Primordial stage ; illustrates the power of locality over life, 

 and opens out the wonderful march of geographic dispersion through ob- 

 stacles innumerable. 



For a long period naturalists have been arranging the life of the globe 

 into species, genera, orders, &c., with a view to the estabHshment of types 

 as standards of comparison. It is from such data, well considered and 

 generally acknowledged, that this * Thesaurus ' has been compiled. 



As long as an individual mollusk remains unregistered it is deprived of 

 its full usefulness ; but even then it may reveal an important fact — as the 

 trilobite speaks of the Palaeozoic period, and a nummulite of the Tertiary. 



* Agassiz, Beyricli, Bronn, Brongniart, Conrad, Dalman, D'Orbigny, Vicomte 

 d'Archiac, Dawson, Emmerich, Emmons, Fischer, E. Forbes, Goldfuss, Green, Hark- 

 ness, Hisinger, Haime, Honeyman, Eupert Jones, Ketley, Kutorga, Lawrow, Linneeus, 

 Loven, Lonsdale, M<=Chesney, Meek, Menegliini, Milne-Edwards, Morris, Owen, 

 Pander, Phillips, Portlock, Eoemer, Eouault, Sars, Sharpe, Safford, Swallow, Triger, 

 Vanuxem, Von Buch, Volborth, Wahlenberg, Winchell, &c. &c. 



2 H 2 



