THYNG: SQUAMOSAL BONE. 
411 
connected with the jugal (not shown in the figure), and of a posterior 
portion which develops upon the otic capsule and with its posterior 
end overlaps the anterior dorsal portion of the quadrate (Qn.). It 
thus fully meets the definition of the squamosal as given on the fore¬ 
going page. 
In the adult of the same genus (pi. 41, fig. 6) the anterior half of the 
supratemporal (St.) is closely applied to the distal external surface of 
the posterior process of the parietal (Pa.). Its posterior inner surface 
adjoins the exoccipital, while a large part of its external surface is 
hidden from view by the hinder portion of the squamosal ( Sq .) which 
lies across it. The squamosal in turn extends forward under the ven¬ 
tral margin of the postorbital (Po.) and nearly meets the posterior 
end of the jugal (/.). If now we compare these relations with the 
conditions given by Baur and Case (’99) in their restoration of the 
Pelycosaur skull (fig. K) we find that in general they are easily recon¬ 
ciled with each other. In both, the supratemporal vacuity is bounded 
anteriorly by the postorbital (Po.), ventrally by the postorbital and 
squamosal (Sq.), behind by the supratemporal (St.), and dorsally by 
the supratemporal and parietal (Pa.). In Sceloporus, however, the 
supratemporal has undergone marked reduction and this seems to be 
true of the Lacertilia as a whole, while in Sphenodon it has disappeared 
entirely. If we accept Williston’s (:04) homologies, the posterior and 
ventral boundary of the supratemporal fossa in the Lacertilia cannot 
be homologous with that in the Rhynchocephalia, while accepting the 
interpretations of the present article they are compared without diffi¬ 
culty. The ventral boundary of the infratemporal fossa of the Rhyn¬ 
chocephalia is lost in the modern lizard. 
The figures of Platycarpus and Liodon as given by Zittel (:02, vol. 
2, p. 158; ’87-’90, vol. 3, p. 615) show that in the Pythonomorphs we 
have practically the same conditions and relations as in the Lacertilia. 
In the skull of the adult Ophidia there is but a single covering bone 
in the temporal region lateral to the parietal and for this as many 
homologies have been given as for either of the two in the lizards. 
It is the mastoid of Cuvier and Owen. Hallmann, Stannius (’56), 
Huxley, Gaupp, Gegenbaur, Gadow, Williston, and many others 
have called it the squamosal; Boulenger has termed it the supra¬ 
temporal and Cope the paroccipital. It develops upon the otic cap¬ 
sule and is in close proximity anteriorly with the parietal, even in the 
embryo. It shows no signs of overlapping the quadrate but rather 
