FOSSIL INVERTEBRATED ANIMALS. 519 



minutest details are pregnant with interest and importance; 

 and, we might add, almost indispensable to the perfect eluci- 

 dation of the subject. 



As to the other sources from which our observations have 

 been derived^ we have not been backward in indicating them 

 in the proper places. We are deeply indebted to several other 

 distinguished naturalists and geologists, as well as to M. Cuvier ; 

 and the names of Buckland and Conybeare, of De la Beche, 

 of Mantell, of Sowerby, of De France, and De Blainville, so 

 frequently referred to in our pages, will serve to prove that we 

 are not insensible to the extent of our obligations. 



On the whole, we have endeavoured to present to our readers 

 as accurate a review as we could of the state of a science 

 which, even yet, can hardly be said to have passed the 

 limits of its infancy. The spirit of scientific discovery, awak- 

 ened in every portion of the civilized world, is continually 

 pouring in new materials, which no prescribed space can com- 

 prehend, and whose rapid succession no individual industry can 

 overtake. In fact, those who attempt to describe the origin, 

 progress, and existing state of any natural science, are in the 

 predicament of writers of memoirs, not in that of historians. 

 There is much relating to the subjects of both, which, though 

 existing, may not be available, and more that is yet undeveloped 

 in the womb of futurity. There is one chance, however, in 

 favour of the memoir-writer, which is denied to him who traces 

 the footsteps of scientific research — he may sometimes hope 

 to outlive his subject and complete his work ; but ages must 

 pass away before human science shall have arrived to its utmost 

 limit of discovery, — even though that limit depend on the finite 

 but still undefinable extent of the faculties of man. He who 

 argues that he can complete the history of any science, is like 

 the rustic, tarrying until the river should pass by — 



. "atille 

 Labitur et labetur in omne volubilis aevum." 



All this is more especially true respecting the subject upon 



