$. V. ARRANGEMENT. 183 



chief, though not the only end, proposed in the 

 investigation of reliquia, is to acquire a knowledge 

 of their several forms, and of their relations to 

 plants and animals of the present day. This, we 

 may remark, must be obtained, before the study can 

 be of use even to the geologist, to whom, according 

 to some authors, it is alone useful For, it is evi- 

 dently of little moment to the geologist to know, 

 that certain substances have been found under an 

 organic form, unless the nature and kind of body 

 imparting that form be also ascertained. It is from 

 this only, as far as extraneous fossils are connected 

 with the subject, that he can reasonably judge of 

 the time and mode of formation of secondary rocks 

 and strata and it is sufficiently apparent, that the 

 knowledge alluded to will be sooner acquired, from 

 an arrangement founded on the affinity of reliquia 

 with the recent subjects, than from one, in which 

 the constituent substance gives the leading divisions, 

 and the nature of the organic body is only a secon- 

 dary consideration. 



This principle of arrangement, according to the 

 nature of the original bodies, . being assumed, the 

 following divisions are necessary for the systema- 

 tical distribution of reliquia CLASS, ORDER, GE- 

 NUS, Family f, SPECIES, VARIETY, Specimen. 



t The primary or leading divisions used by Linnaeus, and now 

 generally adopted in every work on Natural History, are five 

 Classes, Orders, Genera, Species, and Varieties In the arrange- 

 ment of plants and animals, when the species are very numerous 



