PALAEONTOLOGY. 275 



those of the old. Peter Camper, Sommering, and Blumen- 

 bach, had the merit of being the first, by the scientific appli- 

 cation of a more accurate comparative anatomy, to throw 

 light on the osteological branch of palaeontology the archae- 

 ology of organic life; but the actual geognostic views of 

 the doctrine of fossil remains, the felicitous combination of 

 the zoological character with the order of succession, and the 

 relative ages of strata, are due to the labours of George 

 Cuvier, and Alexander Brongniart. 



The ancient sedimentary formations, and those of transition 

 rocks, exhibit, in the organic remains contained within them, 

 a mixture of structures very variously situated on the scale of 

 progressively developed organisms. These strata contain but 

 few plants, as, for instance, some species of Fuci, Lycopodiaceac 

 which were probably arborescent, Equisetacete, and tropical 

 ferns ; they present, however, a singular association of animal 

 forms, consisting of Crustacea (Trilobites with reticulated 

 eyes, and Calymene), Brachiopoda (Spirifer, Orthis], elegant 

 Sphaeronites, nearly allied to the Crinoidea,* 1 Orthoceratites, 

 of the family of the Cephalopoda, corals, and blended with 

 these low organisms, fishes of the most singular forms, 

 imbedded in the upper silurian formations. The family of 

 the Cephalaspides, whose fragments of the species Pterichtys 

 were long held to be Trilobites, belongs exclusively to the 

 Devonian period, (the Old Red); manifesting, according to 

 Agassiz, as peculiar a type amongst fishes as do the Ichthyo- 

 sauri and Plesiosauri amongst reptiles.f The Goniatites, of 

 the tribe of Ammonites,:]; are manifested in the transition 

 chalk, in the greywacke of the devonian periods, and even in 

 the latest silurian formations. 



The dependence of physiological gradation upon the age of 

 the formations, which has not hitherto been shown with per- 

 fect certainty in the case of invertebrata, is most regularly 



* Leop. yon Buch, Gebirgsformationen von Russland, 1840, s. 24-40. 



t Agassiz, Monographie des Poissons fossiles du vieux Ores Rouge, 

 p. vi. and 4. 



J Leop. von Buch, in the Abhandl. der Berl. Akad., 1838, s. 149- 

 168 ; Beyrich, Beitr. zur Kenntniss des Eheinischen Uebergangsge- 

 biryes, 1837, s. 45. 



Agassiz, Recherclies sur les Poissons fossiles, t. i. Inlrod. p. xviii 

 Davy, Consolation in Travel, dial. iii. 



T 2 



