FOSSIL INVERTEBRATED ANIMALS. 491 



names, such as crusfacite, carcinite, Sfc. These fossils, for the 

 most part, are referable to known genera, but not to species 

 yet admitted into our systems of natural history. All that has 

 been written about them to the present day is very vague, and 

 the figures of them which have been given are, in general, far 

 from exact. The majority of naturalists who have mentioned 

 them, wrote at the period when philosophers were only begin- 

 ning to perceive that the parts of the globe which are now dry, 

 must formerly have been submerged ; and all that they pro- 

 posed to prove at that time was, that the different bodies which 

 were found buried, had some analogy with the actual produc- 

 tions of our seas. Thus they did not attach themselves to 

 details, but confined their labours to descriptions and figures, 

 which, bad as they were, always designated marine bodies. 



At present, when, in consequence of the great progress of 

 the natural sciences, a system so much more rigorous is pur- 

 sued respecting the distinction of species and genera, the major 

 part of the labours of preceding naturalists has become almost 

 totally useless, unless very detailed and minute figures are 

 added to them, done by able artists. In fact, with the ex- 

 ception of the figures of Knorr, all that has been pubhshed 

 on petrified Crustacea, by a crowd of authors, is too incomplete 

 to furnish anything like an adequate acquaintance with these 

 sorts of fossils. 



It is not rare to find fossil Crustacea, and their debris more 

 especially, in the most recent as well as in the most ancient 

 strata; but it is not common to find any in a state of com- 

 plete preservation. The fragility of their testa has not often 

 permitted it to be preserved entire in those depositions where 

 so great a number of the relics of other marine bodies are 

 found. These animals appear to be much in the same predica- 

 ment as fish. Those which die naturally become the prey of 

 the different marine animals, of which they constitute the ordi- 

 nary aliment ; and it is only by chance that some of them 

 escape destruction. 



