Cope.] It50 [March IS, 



in contact in all forms except Cliama?leon, towards the middle line. This 

 portion is generally grooved, but in Xenosaurus it is a slender rod. Thej^ 

 are received on the basipterygoid processes of the sphenoid, and then di- 

 verge and assume a longitudinal position witliout meeting on the middle 

 line. They are produced in an angle or process towards the posterior ex- 

 tremity of the maxillary bone, from which they are separated by the 

 ectopterygoid. The pterygoids then join the palatines. In a few genera 

 they bear a few small teeth. The palatines are separate from each other 

 and from the maxillaries, but send^a process outwards and forwards to the 

 latter. They join in front each its corresponding half of the vomer. 

 The internal nares are situated each between the vomer and the maxil- 

 lary, and it notches more or less deeply the palatine, which forms its pos- 

 terior border. The vomers are separate in all forms excepting Cliamaeleon, 

 and they have various forms. In Gecconidse and Anolidoe they are flat 

 and fit closely together, and they have the same character in many 

 Agamidoe and Iguanid*. In a few members of these families (Uromastix 

 and Sauromalus), they are divided by a groove, which becomes a fissure 

 posteriorly, which is the character in most other lizards. In the Varani- 

 dse each vomer is produced posteriori}'- on each side this fissure to a 

 greater distance than in other forms. The planes of the palate differ 

 mucli in different families and groups. Thus the vomer is on a much 

 higher plane than the palatines in Chami'eleouidoe and Gecconidte, the 

 palatines curving downwards to meet the pterygoids. The latter are gen- 

 erally horizontal, but in Chamseleon they are in a subvertical plane, their 

 free rounded extremities descending and fitting on the inner side of the 

 mandible. The}' do not quite reach the quadrate. In the Agamidse, Ig- 

 uanidas and Gecconidtc the internal extremity of the ectopterygoid is di- 

 rected inferiorly, forming a downwardly directed angle on each side of 

 the palate. In the Amphisbtenia the structure of the palate is much 

 more compact than in other lizards. The palatines are in contact on the 

 middle line and there is no palatomaxilhuy foramen. That is, the pala- 

 tine is in close contact with the maxillary, tbe ectopterygoid being tightly 

 wedged in between them. The pterygoids are in contact throughout 

 their length with the sphenoid, and the proximal end of each is tightly 

 wedged between the latter and the quadrate. 



The character of the petrosal mus-t be attended to by anj' one who de- 

 sires to understand the relations of the Lacertilia among themselves. In 

 no member of the Lacertilia is the trigeminus foramen closed anteriorly 

 by bony tissue, but it is enclosed by the membrane which forms the ante- 

 rior wall of the brain case. The petrosal is divided into two parts by the 

 deep notch whose fundus forms the posterior border of this foramen, 

 which may be called the supra- and infraforaminal portions. The infra- 

 foraminal portion is divided in most of the families by a longitudinal, 

 keel-like ridge, which forms the superior border of a groove whose infe- 

 rior wall is formed by the sphenoid. This groove is not present in Helo- 

 derma and is very shallow in Xenosaurus. It is wanting in the Auniel- 



