58 Journal of Entomology and Zoology 
A true squamosal bone is sometimes considered not to exist 
among Amphibia, and the so-called squamosal bone is considered 
to be rather an investing bone on the surface of the quadrate, and 
for this reason is sometimes called the paraquadrate. 
The quadrate (8) is an irregularly shaped little bone with 
somewhat the appearance when in position, of a wedge between the 
ptergoid and the squamosal. Functionally it serves as a piece in- 
terposed between the skull and the mandible, and forming an 
articular surface for the latter. The knob-like anterior ventral 
end of the quadrate consists of an articular process, fitted with 
a socket to receive the rounded knob ( articulare) of the mandible. 
The ptergoid (7) is a spade-shaped bone which projects down- 
ward from the ventral side of the skull. It articulates with the 
main body of the skull by means of a hollow, rounded process which 
articulates down over a knob-like projection on the occipital bone. 
Aside from the articulation with the occipital, the ptergoid articu- 
lates posteriorally with the quadrate and the squamosal. 
The squamo-palatines (13) are long rather slender bones, flat- 
tened anteriorally. At about one-third of their length, from the 
anterior end, they articulate dorsally with the parasphenoid and 
project down onto that bone for the remainder of their length. 
These projections are provided with teeth along the median line. 
Anteriorally the squamo-palatines articulate with the premaxillary 
and the maxillaries. 
The parasphenoid (11) is the flattest and most extensive bone 
in the skull, and forms nearly the whole floor of the brain case, and 
at the same time the roof of the mouth. It is nearly the shape of 
a parallelogram with rounded corners, but it is a little broader in 
the optic region and becomes somewhat narrowed anteriorally. It 
