Notices respecting Ne-iO Books. 447 



parts of which mutually correspond, and concur to produce a certain 

 definite purpose by reciprocal re-action, or by combining towards the 

 same end,' it follows from the peculiar structure of the fossil teeth 

 alone, that the muscles which moved the jaws, and the bones to which 

 they were attached, were widely different from those of any of the 

 living lizards ; and consequently the form of the head of the Iguano- 

 don must have been modified by these causes, and have dift'ered from 

 those of existing reptiles. Since the vegetable remains with which 

 the teeth of the Iguanodon are associated consist principally of those 

 tribes of plants that are furnished with tough thick stems, and which 

 probably were the principal food of the original animal, we may be 

 permitted to remark, that this peculiar structure of the teeth seems to 

 have been required to enable the animal to accommodate itself to the 

 condition in which it was placed. Hereafter, perhaps, some more 

 fortunate observers may discover a portion of the head and jaw, and 

 be able to confirm or refute our conjectures." 



Some bones, &c., supposed to be referrible to the Iguanodon, are 

 next described ; and among them a horn, apparently belonging to 

 that animal. 



"We have now to request the reader's attention," observes Mr. 

 Mantell, " to a very remarkable appendage, with which there is every 

 reason to believe the Iguanodon was provided. This is no less than a 

 horn, equal in size, and not very different in form, to the lesser horn 

 of the rhinoceros. This unique relic is represented of the natural size, 

 Plate XX. fig. 8. It is externally of a dark brown colour ; and while 

 some parts of its surface are smooth, others are rugous and furrowed, 

 as if by the passage of blood-vessels. Its base is of an irregular oval 

 form, and slightly concave. It possesses an osseous structure, and 

 appears to have no internal cavity. It is evident that it was not united 

 to the skull by a bony union, as are the horns of the mammalia. The 

 nature of this extraordinary fossil was for some time unknown ; and 

 it is to the discrimination of M. Pentland, to whom a cast of it was 

 shown by Professor Buckland, that we are indebted for the suggestion 

 that h probably belonged to a saurian animal. It is well known that 

 some reptiles of that order have bony or horny projections on their 

 foreheads ; and it is not a little curious, that among the Iguanas the 

 horned species most prevail. The Iguana cornuta, which is a native 

 of St. Domingo, resembles the common Iguana in size, colour, and 

 general proportions ; on the front of the head, between the eyes and 

 nostrils, are seated four rather large, scaly tubercles ; behind which 

 rises by an osseous conical horn or process covered a single scale*. 

 That our fossil was such an appendage, there can be no doubt ; and 

 its surface bears marks of the impression of an integument by which 

 it was covered, and probably attaciied to the skull. This fact establishes 

 another remarkable analogy between the Iguanodon and the animal 

 from which its name is derived." 



The vertel)raj, teeth, and other bones of some PIcsiosauri, also occur 

 among the fossils described in this work j and the catalogue terminates 



• Shaw's Zoology, vol. iii. Part 1. p. 203. 



with 



