MENOPOMA. SIEBOLDTIA. 191 



parallel with the maxillary teeth. All the teeth are conical, pointed, 

 slightly curved backwards and inwards ; their points glisten with a 

 yellow metallic lustre, whence the name of Chrysodonta proposed for 

 this genus by Dr. Mitchell. (1) 



The Amphiuma means has twenty teeth on each side of the upper 

 jaw, of which fifteen or sixteen are attached to the superior maxillary 

 and four or five to the intermaxillary bones : it has sixteen teeth on 

 each side of the lower jaw. There are fourteen or fifteen teeth in 

 each of the vomerine series. 



The Amphiuma tridactylum (PI. 62, fig. 7) has four intermaxillary 

 and thirty-one or two maxillary teeth on each side of the upper jaw, 

 and twenty-four teeth on each side of the lower jaw. It has twenty- 

 six to twenty-eight teeth in each vomerine series. 



81. Menopoma. — The Menopome (PL 62, fig. 5 and 6), exhibits 

 the same essentially batrachian condition of the teeth as the amphiume, 

 but in their disposition, and in the division and form of the vomer, 

 it makes a nearer approach to the caducibranchiate group, and allies 

 itself most closely with the gigantic newt of Japan, {Sieboldtia, 

 Bonap.) and with that equally gigantic extinct species of newt, so 

 noted in palaeontology, as the Homo diluvii testis of Scheuchzer.(2) 

 In the persistence of the branchial apertures, and the more complex 

 structure of os hyoides, the menopome, however, manifests its 

 generic distinctness from the Sieboldtia. The single close-set series 

 of small, equal, conical and slightly recurved teeth describes a semi- 

 circle on both the upper and lower jaws : the row of similar but smaller 

 teeth on the anterior expanded border of the divided vomer runs 

 parallel with, and at a short distance behind the median part of the 

 maxillary series, (PI. 62, fig. 6). The premandibular teeth are received 

 into the narrow interspace between the two rows in the upper jaw when 

 the mouth is closed. The teeth of the menopome as of the amphiume 

 are anchylosed by their base and part of its outer side to a slightly 

 elevated external alveolar ridge. 



82. Sieboldtia. — The perennibranchiate or fish-like Batra- 

 chians — 'doubtful reptiles' as they have been termed — lead by 



(1) Medical Recorder, July, 1822. 



(2) Philosophical Transactions, xxxiv, (172G), p. 38. 



