ROOM III. 



LOWER JAW OP THE IGUANODON. 



249 



tion of the maxillary organs of the Iguanodon. From the 

 appearance of the fractured end, it seems probable that the 

 dentaiy bone was prolonged 

 backwards five or six inches 

 before it united with the sur- 

 angular and angular : upon 

 this supposition the entire 

 length must have been two 

 feet, and the number of teeth 

 about twenty. In the Iguana 

 and most Lizards the dentary 

 element is half the length of 

 the jaw ; and if this propor- 

 tion be taken as the standard 

 of comparison and it ap- 

 pears to be the most pro- 

 bable one the length of the 

 jaw of this individual was 

 four feet An eminent pale- 

 ontologist 1 has estimated the 

 length of the head of the 

 largest Iguanodon at only 

 thirty inches; having taken 

 as the basis of his calculation, 

 the length of six dorsal ver- 

 tebrae, which in the Iguana 

 is equal to that of the lower 

 jaw. But the specimen be- 

 fore us proves either that the 

 same scale of proportion is 

 not applicable to this co- 

 lossal saurian, or that much 

 larger dorsal vertebrae than 

 those from which the mea- 

 surement was taken, are yet 

 to be discovered ; for several 

 teeth in my possession exceed in magnitude the largest 

 sockets of this dentary bone. Even if we take the abbreviated 

 proportions of the short blunt-headed lizards as the scale 



1 Reports of the British Association for 1841. Article, "British 

 Fossil Reptiles," p. 143. " If there be any part of the skeleton of the 



LIGN. 55. 



RESTORED FIGURE OF THE LO-WER JAW OF 



THE IGUANODON. SEES FROM ABOVE. 



( T V Nat. tize.) 



