Cope.] ^*J* [March IS, 



the only element present in Feylinia (Anelytropsidit). It is always osse- 

 ous. The form of its proximal extremity varies in the different ftimilies. 

 It is simple in the Nyciisaura, Uroplatoidea, Acrodonta, Iguania, Diplo- 

 glossa and Thecaglossa ; and expanded and generally perforate in the 

 other superfamilies where present, except in some degenerate genera 

 where it is simple (see Plate ii, Fig. 2). In Trachysauius and Cophias, its 

 proximal end is dilated but not perforate. The scapula varies in form from 

 elongate to short and wide. It presents a proscapular process in many 

 families and genera. It is present in Iguania and Nyctisaura ; in the last 

 named often decurved and acuminate ; and in Lophura, in Acrodonta. 

 It is present among Leptoglossa in Cnemidophorus, and in some Amivae, 

 while in other Amivte it is wanting. It is wanting generally in Acro- 

 donta, Diploglossa, Tliecaglossa and Leptoglossa, but it is present in 

 Celestus striatus. It is wanting in Rhiptoglossa. The coracoid is ex- 

 tended anteriorly to the sternum, and it is generally deeply emarginate on 

 its anterior interior border. These emarginations are closed by the pro- 

 coracoid, which extends to the middle line, and is only partially or not at 

 all ossified. There are two coracoid emarginations in most Iguania ; 

 exceptions being the terrestrial genera Urocentrum, Sceloporus and 

 Phrynosoma, and the Anolida?. There are also two in Varanidse and 

 Tiid«. The Agamidne generally have but one, but Uromastix is an 

 exception. There is but one in Anguida^ and Scincidte (two in Tiliqua) ; 

 and none in Helodermidje and Cham^leonida!. 



The interclavicle is a very characteristic element in the Lacertilia. It 

 is wanting in Chamseleonidse and in some genera with fore limbs rudi- 

 mental or absent. It is a simple splint in Helodermidas and some degen- 

 erate genera. In other families it has a transverse limb on each side, 

 which may be anterior, producing the " anchor-shaped " form, or median, 

 producing the "cruciform" type. It is anchor shaped in Acrodonta, Ig- 

 uania, and Thecaglossa, and cruciform in Diploglossa and Leptoglossa. 

 In Nyctisaura it is cruciform with the lateral processes wide at the base. 

 The sternum is a broad subrhombic plate which articulates by its antero- 

 lateral borders with the procoracoid and coracoid, and by its posterolateral 

 borders with the ribs. In genera with well-developed limbs its principal 

 differences are seen in the nature of its fontanelles when present. In the 

 Agamidte there are two, and in most Igaanidte there is one. Exceptions 

 are the genera Polychrus, Sauromalus and Dipsosaurus, where there is no 

 fontanelle. There is none in the Anolidte. In Tiida; and Lacerlidte it is 

 present, but in Scincidte it is mostly absent, exceptions being the North 

 American species of Eumeces. The fontanelle is wanting in Gecconidte, 

 Diploglossa, Helodermatoidea, Thecaglossa and Leptoglossa, witli the 

 exceptions above noted. The single median fontanelle is frequently con- 

 cealed by the median limb of the interclavicle. It is nearly divided in 

 some species of Sceloporus. 



4. The Pelvic Arch. — It is characteristic of the Lacertilia that tlie 

 ilium is directed upwards and posteriorly, and that the obturator foramina 



