6 Essay introductory to Geology. 



In the lowest fossiliferous order of formations, of which we are now 

 treating, many peculiar genera exist. An entire distinct family of ganoi- 

 dians is here found, having their vertebral column prolonged at its posterior 

 extremity into a single lobe, which reaches to the caudal. Here also 

 we find fishes more approximating to the type of saurian animals in the bones 

 of their skull and powerful conical teeth ; the remains of true saurians do 

 not, hoivever, appear to be yet found. The teeth from the carboniferous 

 limestone of Burdie house, near Edinburgh, being pronounced by M. 

 Agassiz to belong to these sauroid fish.* 



We also here find those great pointed rays, called ichthyodorulites, here- 

 tofore confounded with the rays of the balistes, but now ascertained by 

 M. Agassiz to have belonged to shark-like fish of the placoidian order j 

 these occur in the very lowest of the fossiliferous beds, but, though with 

 diflerence of specific character, recur throughout the geological series to the 

 chalk inclusive. 



Tlie vegetation of this period appears, from its fossil remains, to have 

 consisted in a very great proportion of vascular cryptogamiae, among which 

 are large tree ferns, allied to tliose which still exist in tropical climates, 

 and the fossil lepidodendra appear to be allied to the lycopodiaceae. A 

 few monocotyledoneae, viz. palms and arborescent liliacege also occur j and 

 in some of our coal formations, Mr. VVitham has also established the exist- 

 ence of coniferae. The whole character of the vegetation is such as we 

 should expect to find prevailing in n. very high temperature and moist 

 atmospliere, under circumstances, in short, analogous to those which cha- 

 racterise tropical islands. 



I have been more minute in my statements concerning the organic 

 remains of this lowest fossiliferous series, (although I have still confined 

 myself rather to general facts than particular details) because the founda- 

 tion being here clearly laid, the elucidation of the organic remains or 

 palaeontology, as it has been termed, of the more recent formations will 

 only require a brief notice. 



The consideration of the animal remains of these earliest deposits, ex- 

 hibiting the very first traces of aniuial life, derives moreover additional 

 physiological importance from the complete refutation it appears to furnish 

 to the extravagant hypothesis of some French naturalists, such as Lamarck 

 and Geoffrey St. Hilaire, concerning the progressive development of the 

 animal kingdom, by the gradual conversion of inferior into the contiguous 

 superior species. It should appear that they consider creative power as 

 incompetent to have produced more perfect forms until he had first tried 



* A saurian vertebra, however, is said to have been found by Mr. Vernon in the 

 carboniferous limestone of Yorlcshire ; can this also have belonged to the sauroid 

 fish of M. Agassiz ? He says that these vertebrae do not resemble tlie saurian ty^Q in 

 the articulation of the spinous process to the body. 



