2. Remove the skin from the roof of the mouth and note the parasphenoid 

 and single vomer, pterygoids, which are large and send leaf-like processes 

 towards the middle line covering the Eustachian passages, squamosals, 

 quadrates, basi-occipital, ex-occipitals, premaxillse, and maxillae. The 

 orbitosphenoid and alisphenoid are well marked. There are no palatines 

 present. 



Maxilla 

 -Orbitosphenoid 



SpheTietnmoid 



-Squamosal 



Exoccipital-' 



Basi-occipital 



Ouadrato-;uga ! 



Exoccip 



FiG. 10. —Ventral view of Skull of Xenopus and Rana. 



[In the Frog there are a pair of vomers bearing the vomerine teeth, palatines, 

 and quadrato-jugals. The pro-otics, which are not seen in a ventral view of 

 the skull in the Platana, being covered over bij the pterygoids, are shown in the 

 Frog.] 



Make a drawing of the ventral side of the skull. 



Orbitosphenoid Frontoparietal Alisphenoid 

 Supraethmo 



Ni 



Frontoparietal 



P.Ieii>oflneek.elian- 



FiG-. 17. — Side view of Skull of Xenopus and Rana. 



3. Make a drawing of the bones of the skull viewed from the posterior 

 end, showing the occipital condyle at each side of the foramen magnum, 

 ex-occipitals, basi-occipital, supra-occipital, pro-otics, columella, and quadrate. 



[In the Frog the basi-occipital and supra-occipital are not developed.] 



4. Remove the skin from the lower jaw and make out the bones sur- 

 rounding the original Meckel's cartilage, viz., the mento-meckelian, dentary, 

 and articular. 



[In the Frog the lower jaw is composed of the mento-meckelian, dentary and 

 angulo-splenial.] 



Make a drawing of the lower jaw. 



38 



