68 MAR8UPIAI.IA. 



There are two linear impressions on the inner side of the 

 horizontal ramus of the jaw of the Phascolothere which 

 have been mistaken for indications of harmonia, or tooth- 

 less sutures, analogous to those which join together the 

 component pieces of the compound jaws of reptiles and 

 fishes. One of these is a faint, shallow, linear impression, 

 continued from between the antepenultimate and penulti- 

 mate molars, obliquely downwards and backwards, to the 

 foramen for the dental artery. I conceive it to be due to 

 an accidental crack ; and if the portions of the bone which 

 it separates were to be compared to the contiguous margins 

 of the opercular and dentary pieces of a reptile's jaw, it 

 would be seen that the only suture, which in Reptiles is 

 continued from any part of the level of the dental series be- 

 tween these pieces, passes in a totally different direction ; 

 it is the suture which bounds the anterior part of the oper- 

 cular piece, and which, in all reptiles, runs obliquely down- 

 wards and forwards, instead of downwards and backwards. 

 The second impression in the jaw of the Phascolotherium is 

 much more strongly marked than the preceding ; it is a 

 linear groove continued from the anterior extremity of the 

 fractured base of the inflected angle obliquely downwards 

 to the broken surface of the anterior part of the jaw. 

 Whether this line be due to a vascular impression, or an 

 accidental fracture, I do not offer an opinion ; but this 

 may be confidently affirmed, that there is not any suture in 

 the compound jaw of a reptile which occupies a corres- 

 ponding situation. 



And lastly, with reference to the philosophy of pronoun- 

 cing judgement on the saurian nature of the Stonesfield 

 fossils from the appearances of sutures in the jaws them- 

 selves, I would offer one remark, the justness of which will 

 be obvious alike to those who are and those who are not 



