66 The Alligator and Its Allies 
the pterygoids behind to the maxille in front. 
They are united with each other by a straight 
median suture and form a considerable part of the 
floor as well as a part of the side walls and roof of 
the nasal passage. They form most of the median 
boundaries of the posterior palatine vacuities (pv). 
Dorsally they articulate with the pterygoids, pre- 
frontals, and vomers. 
The pterygoids (10) are the very irregular bones 
that project ventrad and caudad from beneath the 
orbits. Their suture is continuous, caudad, with 
that between the palatines and at the posterior end 
of this suture is the posterior opening of the nasal 
chamber, the posterior nares (pn). This opening 
is divided by a vertical, longitudinal, bony septum, 
and the part of the chamber into which it immedi- 
ately opens, which lies in the pterygoids, is divided 
by a number of transverse, vertical septa. Poste- 
rior and dorsal to the posterior nares the pterygoids 
are fused. Anteriorly the pterygoids articulate 
with the palatines; dorsally with the quadrates, 
basisphenoid, alisphenoids, and prefrontals, and 
dorso-laterally with the transpalatines. The lat- 
eral vertical border of the pterygoid is roughened 
and is, according to Reynolds, covered, during life, 
with a pad of cartilage against which the medial 
side of the mandible plays. 
The transpalatine (11) is a T-shaped bone articu- 
lating ventrally with the pterygoid and dorsally 
with the maxilla, the jugal, and the postfrontal. 
