232 THE BATH OOLITE PERIOD. CHAP. 



anatomy, excited by De Blainville, rose against its master, and 

 declared Cuvier to be wrong, and the jaws to be not mammalian, 

 but reptilian, or even ichthyan u . 



Even Agassiz admitted these objections to some extent, and 

 wished at least to reduce the mammalian rank of the creatures from 

 truly land animals to littoral seals or marine cetacea x . And Grant 

 employed elaborate arguments in favour of their reptilian origin 7. 



Valenciennes z replied to the opposition of Blainville, who quickly 

 rejoined with new doubts a , and a final preference for the opinion 

 that the jaws were those of saurians, or even fishes. 



It must not be thought that this diversity of opinion among 

 competent anatomists implies want of candour, or want of research. 

 In fact, the problem was and is a singularly difficult one. For 

 they had to decide on the affinities of the animal from a knowledge 

 of only one element of its structure the lower jaw with its teeth. 

 Can we, it may fairly be asked, from a lower jaw with teeth, 

 unsupported by any other part of the bony fabric, infer with suf- 

 ficient probability the class, order, and family of animals to 

 which a specimen belongs ? The answer is affirmative : the process 

 is by marked steps, some of which may be here stated, the full 

 arguments having been clearly given by Owen in his admirable 

 work entitled ' British Fossil Mammals/ 

 It must be one of the vertebrata. 



It cannot be one of the class of fishes, because of the teeth which 



are of three orders, molars, premolars, and incisors, and because 



of the double fangs of the molars deeply implanted in bony 



sockets. 



The same circumstances are decisive against a reference of the 



jaw to birds, chelonians, serpents, and batrachians. 

 In existing nature we have therefore only to look into the saurian 

 reptiles, or some order of mammalia, and to consider these 

 classes in regard to dentition and the structure of the lower 

 jaw-bone. 

 The teeth of living reptiles are extremely variable, but they 



u Doutes sur le pretendu Bidelphe Fossile de Stonesfield. Comptes rendus, 1838, 

 August 20. 



x German Translation of Buckland's Bridgwater Treatise. 



y Thomson's British Annual, 1839. 



1 Cooiptes rendus, 1838, September. a Comptes rendus, 1838, October 6. 



