A NEW THECODONT REPTILE: 1077 
light on the nature of the lacertilian post-temporal bones. The 
upper arch is formed mainly by the postorbital but partiy by a 
lower bone which I regard as squamosal. Whatever this lower 
bone is, it is quite certainly the homologue of the outer post- 
temporal bone of the lizard, and as there is a quadratojugal still 
lower down, it cannot be the quadratojugal. From its relations 
to the quadrate, there seems little doubt but that it is correctly 
identified as the squamosal. 
The bone internal to it may be the so-called ‘ supra-temporal,” 
but from its articulating with the paroccipital it seems much 
more likely to be the tabular. 
Youngina may be regarded as the type genus of a new family, 
which may be called Younginide, and it must also be placed in a 
new suborder of the Thecodontia, which may be called the 
KosucHIA. 
The Eosuchia may be defined as Thecodont reptiles which have 
no antorbital vacuity, and retain the interparietal and tabular 
bones, and have a large pineal foramen.” 
