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nitors have only eleven or twelve; and the crocodiles have fifteen, which 

 are very unequal. In this jaw also are from ten to twelve large and pretty 

 regular holes. In the Monitors are six or seven, and in the Crocodiles a 

 considerable number of small and irregular openings ; whilst in the Dol- 

 phins there are but two or three, which are towards the end. 



At p is an obtuse raised coronoid apophysis, the anterior ridge of which 

 is enlarged, as in the monitors. In the crocodiles there is nothing similar, 

 in the dolphin it is smaller and much backwarder, and in the iguana it 

 is more pointed. The articulating surface, r, is concave, and very near 

 the posterior end, as in all the lizards ; but it is lower than the dental 

 edge, as in the monitors ; in the crocodiles, and in the iguanas it is higher. 

 In the dolphins it is convex, and placed quite at the end. The apo- 

 physis b, for the attachment of the muscle analagous with the digastric, 

 is short, as in the iguana; in the crocodile, it is longer; and still more 

 so, -in the monitor. 



The formation of the lower jaw shows that this animal more nearly 

 accorded with the monitors than with any other of the lizard tribe : as 

 to the cetacea, there exists no resemblance; since in these, as in all the 

 mammalia, each side of the lower jaw is in one piece. But to be con- 

 vinced of the closer agreement of the lower jaw of the fossil animal with 

 that of the monitor than with that of the crocodile, it is necessary to attend 

 to the following comparison. 



In the lower jaw of the crocodile are six bones on each side : the dental, 

 in which are formed the alveolae of the teeth, the two being articulated 

 with each other in the fore part, and forming the anterior angle ; the 

 opercular , which forms almost all the inner surface of the jaw, except on 

 the fore part where it is formed by the dental ; the coronoidal, with the 

 angular; the former placed over the latter, reaching to the posterior extre- 

 mity; leaving between them a space in the fore part, which is occupied 

 forwards by the- end of the dental, and forms in the back part a large 

 oval hole. The angular bone curves upwards, to occupy a space in the 

 inside of the jaw. Between this bone and the opercular is another oval 



