ANATOMY OF VERTEBRATES. 



131 



gular,' fig. 92, 29 ; of an ( angular ' continued into a f splenial,' ib. so ; 

 of a ' coronoid,' ib. 29' ; and of a f dentary,' ib. 32. All Chelonia 

 are edentulous : the alveolar borders of both upper and lower 

 jaws are sheathed with horn : but in a few species, especially the 

 soft turtles ( Trionyx, Tetronyx} these borders are notched or pro- 

 duced into tooth-like processes. The dentary elements coalesce 

 at the symphysis ; which, in the Snappers, especially Chelydra 

 ( Chelonura) Temminckii, is produced into a sharp hook. 



The hyoid arch consists of a basihyal, fig. 92, 41, a pair of short 



92 



ii 



Side view of cranial vertebras, Emys 



processes, ib. e, giving attachment to the genio- and hyo-glossi 

 muscles : of a pair of long ceratohyals, 40, by which the arch is 

 suspended to the mastoids ; and of a pair of hyobranchials, 47. To 

 complete the series of skull-bones homologous with those of the 

 fish, represented in fig. 81, it is necessary to bring forward the 

 scapular arch which had receded a short distance from its vertebra 

 in the Batrachia, fig. 42, 52, from a more remote position in the 

 Chelonia : we then find that 51, fig. 92, answers to the scapula, 

 fig. 81, 51 ; and that 52, fig. 92, answers to the coracoid, fig. 81, 52 : 

 the diverging series of many-jointed rays in the fish, fig. 81, are 

 now developed into the fore-limb, fig. 92, 53 58. 



K 2 



