506 PROCEEDINGS OF SCIENTIFIC SOCIETIES. 
the development of this element in the Dicynodons and Ichthyosaurus, 
where it had heretofore been erroneously determined. ‘Thus in Ichthyo- 
saurus it was the ‘*‘supratemporal” of Owen, e besides forming the 
posterior i of the zygomatic arch it descended posteriorly to about 
opposite the middle of the posterior face of the os-quadratum. Further 
reaching round nearly or quite to the postfrontal, and sending down a 
columella to the pterygoid. This supero-anterior portion was the parie- 
talof Ow The true parietal was in advance of this, and embraced 
the usual vpisa while the frontals were the nasals of Owen. The 
Fig. 105.* 
true nasals he i i in small bones, one at the posterior extremity 
of each exterior nostril. 
` Turning to the Dicynodont genus Lystrosaurus, he stated that the form 
of the squamosal bone was very similar to that seen in Ichthyosaurus, 
quadratum when viewed f nd; the latter was small and occupied 
a position at the inferior extre on the intero-anterior side of the 
squamosal, and was hed to the pterygoid iny dly He hought 
Urodela, and Dipnoi, which Huxley had suggested was the preoperntm 
of the Teleosts, was truly the squamosal of the higher verte 
the presence of the parietal arches as distinct from the opisthotics was 
insisted on, they having been united by Owen. He then gave new deter- 
* Fig. 105.—Iehthyosaurus; lateral view (fi peci from B , Leicestershire). 
x. . Premaxillary bone. nadra tojugal 
Mx... Maxillary. Geos ses Qua oe her 
x B — DD. «v ec cipio 
Hus ve Prefrontal. jesus TTA : : 
. stfroi An.... Angular, 
£t SIN etal. l Àr, . . . Articular. 
Ta ...Lachrymal. S. Ar.. etas e ERR 
*.. Malar. Pter. . Pterygoid. 
