THE SKELETON 37 



Remove the lower jaw and identify the following bones on 

 the ventral surface of the skull: 



220. Articulating with the premaxillarics are the tooth- 

 bearing vomers (D). 



221. Caudal to these are the thin splint-like palatines 

 (D). 



222. The longitudinal parasphenoid (D) extends caudad. 



223. The triradiate pterygoids (S) articulate with the 

 maxillaries and nasals cephalad, the parasphenoid 

 mesiad, and the quadrato-jugal at the angle of the 

 jaw. 



In a wet specimen note also the folloiuing cartilages from 

 which the derm-hones have been removed: 



224. The nasal capsule (N) surrounds the nose. 



225. The auditory capsule (N) surrounds the ear. 



225. The subocular arch (N) connects the nasal and 

 auditory capsules with the quadrate cartilage (219). 



227. The hyoid cartilage (S) supports the tongue. 



Drawing 19. Draw the left half of the skull from the 

 ventral aspect (x2). 



Examine the vertebral column, consisting of ten bones. 



228. The atlas supports the skull. This is the only cervi- 

 cal vertebra the frogs possess. 



229. There are seven abdominal vertebrae. Note the 

 dorsal neural spines, the cephalic processes (pre- 

 zygapophyses), caudal processes (postzygapo- 

 physes), and lateral transverse processes (diapo- 

 physes). The latter articulate with short cartilages 

 sometimes considered ribs.^ 



230. The sacral vertebra has, united to it, the ilium of 

 the pelvis (242). 



* See Kingsley, The Vertebrate Skeleton, p. 41. 



