TEETH OF REPTILES. 391 



base of the contiguous attached tooth, causes a progressive 

 absorption of that part, and finally undermines, displaces, and 

 replaces its predecessor. The number of nascent matrices of the 

 successional teeth is so great in the Frog, and they are crowded so 

 close together, that it is not unusual to find the capsules of con- 

 tiguous tooth-germs becoming adherent together, as their ossifi- 

 cation proceeds. After a brief maceration, the soft gum may be 

 stripped from the shallow alveolar depression, and the younger 

 tooth-germs in different stages of growth are brought away 

 with it. 



The mode of development of the teeth of serpents does not 

 differ essentially from that of the teeth of the Batrachian above 

 described, except in the relation of the papilla? of the suc- 

 cessional poison-fangs to the branch of the poison-duct that 

 traverses the cavity of the loose mucous gum in which they are 

 developed. 



Some of the peculiarities of the dentition of the Batrachians 

 have already been noticed, as in the comparison of the Siren 

 with the Lepidosiren, in which the true amphibian was shown 

 to have numerous teeth on the palate and lower jaw. 1 The 

 piscine character of rasp-like teeth aggregated in numerous 

 series, is manifested also in the Axolotl, 2 upon the palatal region 

 of the mouth, and upon the splenial or opercular element of the 

 lower jaw ; but the superior maxillary bones are here developed, 

 and also support teeth. The premandibular and the premaxillary 

 bones, instead of preserving the larval condition of the horny 

 sheath, have their alveolar border armed with a single row of 



7 o 



small, equal, fine and sharp-pointed denticles, which are continued 

 above, along the maxillaries ; thus establishing the commence- 

 ment of the ordinary Batrachian condition of the marginal teeth 

 of the buccal cavity. The dentigerous bones of the palate consist 

 of two plates on each side, as in the Siren ; the anterior pair, or 

 vomerine bones, converge and meet at their anterior extremities ; 

 the minute denticles which they support are arranged quincun- 

 cially ; the posterior pair of bones are continued backwards 

 according to the usual disposition of the pterygoids, to abut 

 against the tympanic bones ; the denticles are confined to the 

 anterior part of their oral surface, and resemble in their arrange- 

 ment and anchylosed attachment those of the vomerine series, of 

 which they form the posterior termination. 



In the Menopome, fig. 265, the teeth are small, pointed, in a 



1 V; pi. 62, figs. 5 & 6. 2 Ib. pi. 62, fig. 4. 



