190 PROTEUS. AMPHIUMA. 



is made by the arrangement of the teeth in a single row both upon 

 the roof and at the margins of the mouth. The intermaxillary bones 

 are produced backwards, and the single series of small pointed teeth 

 which they support is opposed to a similar series upon the premandi- 

 bular bones below ; to which elements of the lower jaw the teeth are 

 henceforth confined in the class of reptiles. The palatal teeth form a 

 single row on each of the broad bones, which correspond with those 

 described by Cuvier as the divided vomer in the higher Batrachians, 

 and extend backwards upon the pterygoids, which support a few 

 teeth. 



79. Proteus. — The Proteus anguinus, (PI. 62, fig. 3.) though re- 

 taining like the three preceding genera its external gills, offers a further 

 advance to the dental characters of the higher Batrachians, especially of 

 the amphiuma. The alveolar border of each intermaxillary bone is 

 armed with a row of eight or ten minute and fine sharp-pointed teeth : 

 each premandibular bone supports a greater number of similar but larger 

 teeth, likewise arranged in a single row. The palatine bones, or the 

 two vomers of Cuvier, support a row of denticles, similar and parallel 

 to the intermaxillary crescentic series : but the horns of the palatal 

 dental crescent are continued much further back, and terminate as in 

 the menobranchus, on the anterior part of the pterygoid bones : each 

 half of the crescentic, or chevron shaped series, contains twenty-four 

 teeth. The superior maxillary bones are represented in the proteus 

 by mere cartilaginous rudiments. 



80. Amphiuma. — The Amphiume, like the proteus, presents the 

 batrachian disposition of the teeth in a single close-set series along 

 the alveolar border of both upper and lower jaws ; but the upper series 

 is extended along well developed maxillary, as well as intermaxillary 

 bones ; and in the extent of the maxillary and palatal series of 

 teeth, especially in one species of amphiume {Amph. tridactylum) , 

 there may be discerned the indication of a character which is of much 

 interest in regard to the affinities of an extinct race of gigantic Batra- 

 chians with biconcave vertebrse. The palatal teeth in the amphiume 

 are arranged in a single close-set row along the lateral margins of the 

 vomer, meeting at an acute angle at its anterior part, from which the 

 series extends backwards on either side nearly longitudinally and 



