Manchester Memoirs, Vol. Ivii. (191 2), No. 1. 3 



powerful process, the processus basipterygoideus, which 

 has a well-marked, smooth, articulating face on its 

 anterolateral side : deeply impressed on the bone on the 

 inner side of each of these processes is a groove which 

 leads round from the side of the basis cranii to open in 

 front into a foramen passing through the bone, which is 

 undoubtedly the carotid foramen. In advance of this 

 region the bone is laterally compressed and transformed 

 into a deep plate articulating above with the roof of the 

 skull and appearing on the palate for about half the length 

 of the skull. 



The Pterygoid is a very large bone forming the 

 greater part of the palate. It articulates by a well-marked 

 facet with the basisphenoid exactly as does that of 

 Sphenodon. From this region it passes forward as a broad 

 flat plate apparently touching the parasphenoid for some 

 distance and certainly having a long articulation with its 

 fellow in front. The posterior part of the pterygoid is 

 bent round so as to reach the top of the skull. It unites 

 with the squamosal to form a floor to the otic cavity and 

 passes backwards with the squamosal to the quadrate. 



The quadrate is a large bone, which only appears for 

 a small area on the upper surface of the skull, where it is 

 overlapped by the pterygoid and has a strong sutural 

 attachment to the quadratojugal and squamosal by a 

 much-thickened edge. On the under surface it has a 

 larger exposure, passing upwards on the under surface of 

 the roof of the skull until its upper end is received in a 

 slit in the squamosal, which thus covers it both dorsally 

 and ventrally. The posterior end of the bone is thickened 

 and forms an articulating surface. The relations of the 

 bones are shown in the drawing {Plate). 



This is, I believe, the first complete account of the 

 quadrate in a Carboniferous or Permian Stegocephalian. 



