186 



PALEONTOLOGY 



and principally m the skull. This is joined to the atlas by 

 the medium of two tubercles, developed exclusively from the 

 ex-occipitals ; the bony palate is formed chiefly by two broad 

 and flat bones (fig. 65 a, c), called "vomerine," and generally 

 supporting teeth. It is only in the Batrachians among existing 



reptiles that examples are 

 found of two or more rows 

 of teeth on the same bone, 

 especially on the lower jaw 

 {Cce cilia, Siren). With re- 

 gard to vertebral characters, 

 no such absolute batrachian 

 modifications can be ad- 

 duced as those above cited 

 from the anatomy of the 

 cranium. Some Batrachians 

 have the vertebra? united 

 by ball-and-socket joints, 

 as in most recent reptiles ; 

 others by biconcave joints, 

 as in a few recent and most 

 extinct Saurians. Some 

 species have ribs, others 

 want those appendages ; 

 the possession of ribs, there- 

 fore, even if longer than 

 those of the Cceczlia, by a 

 fossil reptile combining all 

 Fig. 66. the essential batrachian 



Canine tooth of the LabyrintJwdon Jagaeri characters of the skull, 

 ("•*■■««•) would not be sufficient 



ground for pronouncing such reptile to be a Saurian. Much 

 less could its saurian nature be pronounced from the circum- 

 stance of its possessing large conical striated teeth : the ordi- 



