ON BRITISH FOSSIL REPTILES. 19? 



views of the origin of animated species ; but of no stream of science is it 

 more necessary, than of Paleontology, to ' drink deep or taste not*.' 



Of all vertebrated animals, the Reptiles form the class which is least fixed 

 in its characters, and is most transitional in its range of modifications ; the 

 lowest organized species are hardly distinguishable from fishes, and the highest 

 manifest so great an advance in all the important systems of their organism, 

 tliat naturalists are not yet agreed as to whether reptiles ought to remain in 

 one class or form two. Reptiles are, besides, the only class of vertebrate ani- 

 mals in which certain species undergo, after birth, a metamorphosis as singular 

 and extreme as in insects. 



If the progressive development of animal organization ever extended be- 

 yond the acquisition of the mature characters of the individual, so as to abro- 

 gate fixity of species by a transmutation of a lower into a higher organiza- 

 tion, some evidence of it ought surely to be obtained from an extensive and 

 deep survey of that class of animals which, Avhilst intermediate in organization 

 between fishes and mammals, prevailed most on the earth during the long 

 periods that intervened between the time when the only vertebrate animals 

 were fishes, and the tertiary and modern epochs when mammals have become 

 abundant, and have almost superseded reptiles in the herbivorous and carni- 

 vorous departments of the economy of nature. 



In accordance with this not unreasonable expectation, the reptiles of the 

 Magnesian conglomerate and New Red Sandstone ought to have been organi- 

 zed according to the type of the most fish-like perennibranchiate Batrachians ; 

 and the Fishes of the older strata, if they tended to a higher stage of deve- 

 lopment, ought, upon achieving the passage to the Reptilian class, to have 

 entered it at its lowest step. 



It is true, indeed, that the most characteristic Reptilian remains of the 

 New Red Sandstone do belong essentially, as by their double occipital con- 

 dyle, their vomerine palatal bones and teeth, &c., to the Batrachian order; 

 but had the Labyrinthodonts now existed, instead of ranking as the lowest 

 members of that order, they would most unquestionably have been esteemed 

 the highest. And, as in the existing diversified order of Batrachia, one family f 

 represents Fishes, a second | Serpents, a third genus § Chelonians, and a 

 fourth II Lizards; so would the now lost Labyrinthodonts have formed Ba- 

 trachian representatives of the highest order of Reptiles, viz, the Crocodilians. 

 Here, therefore, we find the Batrachian making its first appearance under its 

 highest, instead of its lowest or simplest conditions of structure. To use the 

 figurative language of the transmutation theory, the Labyrinthodonts are de- 

 graded Crocodiles, not elevated Fishes. 



But the hypothetical derivation of reptiles from metamorphosed fishes is 

 more directly negatived by the fact, that the Batrachian type is not that 

 under which reptiles make their first appearance in the strata which succeed 

 the coal-measures. The Monitors of the Thuringian Zechstein are older than 

 the Labyrinthodonts of the Keuper ; and among British Reptiles, the theco- 



* The following are the latest terms in which the transmutation-theory has been promul- 

 gated, as supported by Pala;ontology : — " The life of animals exhibits a continued series of 

 changes, which occupy so short a period that we can generally trace their entire order of 

 succession, and perceive the whole chain of their metamorphoses. But the metamorphoses 

 of species proceed so slowly with regard to us, that we can neither perceive their origin, their 

 maturity, nor their decay; and we ascribe to them a Icind of perpetuity on the earth. A 

 slight inspection of the organic relics deposited in the crust of the globe, shows that the 

 forms of species, and the whole zoology of our planet, have been constantly changing, and 

 that the organic kingdoms, like the siirtace they inhabit, have been graduallydevcloped from 

 a simpler state to their present condition." — Dr. Grant's Lectures on Comparative Anatomy, 

 Lancet, 1835, p. 1001. 



t Perennibranchiata. + Cccilladx. § Pipa. || Salamandra. 



