290 Royal Society : — 



Shumard, and Davidson — together with those of other authors, some 

 of whom are scarcely of inferior merit*. 



I have been favoured with many unpubhshed 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, K.E.), from West Tasmania (Dr. Milligan), from 

 South Wales (Henry Hicks, Esq.), and from the late Mr. Wyatt- 

 Edgell. 



I propose to give to this effort the name of "Thesaurus Silu- 

 ricus." 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 discovering regional affinities, differences, 

 and those great zoological severances 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 universality (as defined) at times 

 proximate everywhere, brings into prominence the riches, magnitude, 

 and wide diffusion of the Primordial stage ; illustrates the power 

 of locality over life, and opens out the wonderful march of geogra- 

 phic dispersion through obstacles innumerable. 



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

 globe into species, genera, orders, &c., with a view to the establish- 

 ment 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 de- 

 prived of its full usefulness ; but even then it may reveal an important 

 fact — as the trilobite speaks of the Palteozoic period, and a nummulite 

 of the Tertiary. 



Until some such record as the present is available, the labours of 

 many living investigators (whose names rise to the lips spontane- 

 ously) will rest comparatively fruitless. It has hitherto not been 

 possible to consider widely scattered existences in an aggregate form. 

 Facts (many) have been stored up separately ; but generalized truths 

 have been rarely attained. This has not yet been done in a satis- 

 factory manner, not even by Bronn or Goldfuss for any one epoch, 

 and scarcely for the cretaceous period by the American geologist 

 Mr. Gabb, although he has dene well. 



*• Agassiz, Beyrich, Eronn, Brongniart, Conrad, Dalman, D'Orbigny, Yicomte 

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

 Ilarkness, Hisinger, liaime, Honeyman, Kupert Jones, Ketley, Kutorga, Lawrow, 

 Linnajus, Lov^n, Lonsdale, M'^Chesney, Meek, Meneghini, Milne-Edwards, 

 Morris, Owen, Pander, Phillips, Portlock, Eopmer, Eouault, Sars, Sharpe, 

 Safford, Swallow, Triger, Yanuxem, Von Buch, Yolborth, Wahlenberg, Winchell, 

 &c. &c. , 



