THE NECTURUS 9 



quadrate. The anterior, outer surface bears a number of 

 teeth and completes the dentition of the upper jaw at the 

 posterior end. The anterior, inner surface articulates with 

 the vomer. The posterior end of the dorsal face has the 

 articulating surface for the quadrate. This articulation is 

 of the flat contact type. There is a small articulating sur- 

 face at the posterior inner edge for the prootic and a small 

 attachment on the outer edge with the quadrate cartilage. 

 The bone forms the anterior brace for the quadrate. 



Quadrate 



The quadrate is firmly joined to the ventral side of the 

 squamosal by a long, flat surface articulation. These bones 

 can be separated with a little care in softened specimens. 

 The quadrate is an awl shaped bone, large at the anterior 

 end where the articulating surface is situated and thin and 

 pointed at the posterior end. A concave surface, well 

 covered with cartilage supplies the articulation with the 

 articulare. 



The dorsal surface has a narrow, articulating face for the 

 squamosal. Anteriorly it articulates with the palato- 

 pterygoid. 



Squamosal 



This is a long, thin, curved plate of bone that is very 

 regular in shape, with the exception of the knob on the 

 inner ventral surface for the articulation of the stapes. 

 The ventral side of the bone bears a long, flat, contact 

 with the quadrate, to which it is very firmly attached. 

 The anterior end is in contact with the palato-quadrate 

 and the posterior with the opisthotic. It forms the pos- 

 terior brace for the quadrate by uniting it to the posterior 

 end of the skull. 



