DIVISIONS OF THE VERTEBRATA. 36 1 



malia, however, diflfer from the Sauropsida in the fact that the 

 skull articulates with the vertebral column by two occipital 

 condyles ; each ramus of the lower jaw is simple, composed of 

 a single piece, and the lower jaw is united with the temporal 

 (squamosal) element of the skull, and is not articulated to a 

 quadrate bone. There are special glands — the mammary 

 glands' — for the nourishment of the young for a longer or 

 shorter period after birth, and the red blood-corpuscles are 

 non-nucleated. 



