ROOM III. TEETH OF REPTILES. 161 



work I must refer the general reader desirous of acquiring 

 more particular information respecting the specimens to be 

 reviewed in the present chapter : for anatomical details, and 

 explanations of all the technical terms employed to designate 

 the respective parts, would extend this volume beyond the 

 limits of a hand-book. 



TEETH OF REPTILES. The teeth, from their dense struc- 

 ture, are the most durable parts of the skeleton, and these 

 organs occur even in rocks of immense antiquity, in the most 

 beautiful state of preservation ; and the various modifications 

 of form and structure, and implantation in the jaws, obser- 

 vable in the existing tribes, are found in the extinct races. 1 

 They exhibit considerable diversity of shape, but the 

 characteristic type is that of a simple cone, with either a 

 rounded or pointed apex, and a single fang ; for no known 

 reptile, whether fossil or recent, has a tooth with the base 

 terminating in more than one root, and that is never bifur- 

 cated. 



These dental organs are only fitted for seizing and retaining 

 the prey or food; for no living reptiles have the power of 

 performing mastication. In the Crocodile the tooth has 

 a cylindrical shank, and a conical, longitudinally striated, 

 enamelled crown, with a ridge on each side. In the Hylce- 

 osaurus, the shank is cylindrical, and the crown expanded and 

 lanceolate, with blunt margins ; in the Megalosaurus the 

 tooth is laterally compressed, trenchant, and bent backwards 

 like a sabre, with serrated edges ; in the Iguanodon the shank 

 is subcylinclrical, and the crown of a prismatic form, greatly 

 expanded, with broad denticulated edges, and a few longi- 

 tudinal ridges in front ; in the Serpents, the teeth are very 

 long and pointed ; in the Lizards, may be seen every modifi- 

 cation of the conical form, down to a mere hemispherical 

 tubercle or plate. The Turtles are edentulous, i.e. destitute 

 of teeth : their masticating organs consisting of the horny 

 trenchant sheaths with which the jaws are covered. 



There are five essential modifications in the mode of 



1 Teeth of Reptiles. See " Medals of Creation," vol. ii. p. 688. 

 Lower Jaw of Reptiles. Ibid. p. 694, Lign. 137. 

 Vertebra of Reptiles. Ibid. p. 695. 

 Sacrum, &c. Ibid. p. 699. 

 Dermal bones. Ibid. p. 701. 



M 



