Cope.] ^^^ [March 18, 



gemlnal foramina. The two together may be homologous with the mam- 

 malian alisphenoid. The epipterygoid is present in all Lacertilia except- 

 ing the Chamgeleonidse and Annulati (Amphisboenia). Its superior con- 

 nections are quite characteristic of the different families. Inferiorly it 

 rests on the pterygoid posterior to its ectopterygoid process, excepting in 

 the GecconidfE, where its point of attachment is opposite to that process. 

 In the same family it does not reach the parietal, but the superior ex- 

 tremity rests on the apex of the suprafnraminal part of the petrosal. In 

 the remaining families there are three modes of superior attachment. In 

 most of the Iguania and Acrodonta it reaches the parietal and does not 

 touch the short petrosal. In the other superfamilies it is in contact with 

 the petrosal. In the Varanidae, Heloderinidse and most Anguidtie it 

 reaches the parietal, which does not meet it with a conspicuous descend- 

 ing process. In Scincidse and Tiidse a conspicuous descending process 

 meets it. In a certain number of genera of various families it does not 

 quite reach the parietal. Such are Eublepliaridse, Gerrhosauridae, Anguis, 

 Lacerta, Phrynosoraa (where it rests on the arcade of the petrosal). Igu- 

 ana, Uronmstix, Agama and Gonyocephalus (sub cr (status). In Lyrioceph- 

 alusand Phrynocephalus the epipterygoid is verj^ short. 



The semicircular canals perforate the supraoccipital, the exoccipital and 

 the petrosal. The internal is in a subtransverse vertical plane, causing a 

 convexity on the internal side of the supra- and exoccipitals, and in some 

 types a visible rib on the superoexternal surface of the same. The 

 external canal is in a horizontal plane and perforates the base of the exoc- 

 cipitopetrosal suspensoriuni, causing a horizontal rib on the anterior foce 

 of the latter in some forms. Tlie anterior is in a vertical anteroposterior 

 plane, and perforates principally the petrosal, occupying its anterior 

 border, which forms the "arcade" in most of tlie thick-tongued super- 

 orders, but crossing the bone much behind the anterior border in the 

 slender-tongaed superorders and the Diploglossa. The fenestra ovale is 

 tightly closed by the disk of the stapes, which is continued externally as 

 the rod-like columella. This rod is slender except in Anniella, where it is 

 remarkably robust. In the other Amphisboenia its tjnnpanic extremity is 

 somewhat thickened. The columella is continued externally into a carti- 

 lage which is more or less expanded in the vertico-transverse plane, the 

 distal portion always so, forming a vertical lamina in contact with the tym- 

 panic membrane. This is the epistapedial cartilage. It is frequently pro- 

 duced upwards beyond its point of attachment into a suprastapedial pro- 

 cess. The plate thus formed is almost separate from the proximal axial part 

 of the cartilage in Heloderma.* The axial portion has a descending pro- 

 cess, the infrastapedial of Parker, in Lacerta, Heloderma, but not in Eu- 

 blepharis, Thecadactylus and Phyllodactylus. 



The rami of the loioerjaw are united at the symphysis by ligament only. 

 The angle is a prolongation of the articular bone ; it is elongate and simple, 



* Memoirs U. S. Natl. Academj^ Sciences, 1S84, Vol. iii. 



