7^ ORGANS OF SUPPORT, 



has its basilar part divided by a vertical suture, and is se- 

 curely united to the atlas by two prominent condyles (b, b,) 

 belonging to that portion 



vi r- *3ft 



of the bone. The parietals 

 (c 9 c 9 ) are long, narrow, near- 

 ly separated by a sagittal 

 suture, arid extend forward 

 over a large portion of this 

 lengthened narrow cranium, 

 as we see also in ophidian 

 and saurian reptiles. The 

 sphenoid bone has also a 

 very lengthened form along 

 the base of the skull, as in 

 fishes. On the fore part of 

 the skull are the two posterior frontals (a,) separate in the 

 young frogs, but united into a single bone extended between 

 the parietals (c, c,) and the two anterior frontals (h, h,) which 

 extend laterally to the two pterygoid, and the two upper 

 jaw-bones (&, k.) The two intermaxillary bones (/,/,) the 

 two upper jaws (k, k,) and two bones behind these, regarded 

 as divisions of the vomer, are provided with small, sharp, 

 recurved conical teeth, although none are found opposed to 

 them in the lower jaw. The slender jugal bone (o,) is ex- 

 tended from the upper jaw bone backwards and downwards 

 to the lower end of the long tympanic (,) which is here 

 moveable, as in most oviparous vertebrata. The tympanic 

 bone (n,) here, as in most of the lower vertebrata, sends 

 down a condyloid process to be articulated with a glenoid 

 cavity (/,) on the back part of the lower jaw. The lower jaw 

 is divided at the symphisis, and each lateral portion consists 

 of an anterior (s,) a middle (r,) and a posterior (/,) piece, 

 which extend to a great distance transversely, and are en- 

 tirely destitute of teeth, although there are teeth in the 

 lower jaw of the salamander and the proteus. As we pro- 

 ceed upwards through the vertebrated classes, the teeth 

 become more circumscribed in their number and in their 

 distribution over the parietes of the mouth, till we find them 

 confined to a single row disposed along the upper and lower 

 jaws. We thus observe in the adult anurous amphibia a 

 greater consolidation of the whole texture of the bones, 



