TEIlDJi. 



331 



phisbsenian type : the pterygoids are largely in contact with the 

 sphenoid, the arches are very weak, the columella is so reduced as 

 to be hardly distinguishable, and the whole sliull forms an almost 

 continuous solid mass. 



The pramaxillary bono is single, the nasals double, the frontal 

 and the parietal single ; a small supraorbital Ijone exists in some 

 Araeivas ; the palatines are in contact anteriorly ; the maxillary is 

 excluded from the infraorbital fossa, which is bounded by the pala- 

 tine, pterygoid, and transverse bono, as in Varanus. The head- 

 shields are always free from the cranial ossification, a character 

 which separates sharply this family from the Old-World Lacertidce. 



Limbs, or their rudiments, are present ; the degradation begins 

 with Proctoporus^ which has very short limbs, but with five well 

 developed clawed digits ; the limbs are still more reduced in size in 

 Scolecosaunis, and the digital formula is incomplete, although claws 

 are still present; in Coj>liias and Ojpliiognomon, digits are either 

 entirely lost or reduced to bud-like rudiments ; and in a species of 

 the latter genus, the pelvic limbs have altogether disappeared. The 

 clavicle is dilated and perforated proximally ; however. Cope men- 

 tions Trctioscincus and a species of Scolecosaurus as forming excep- 

 tions, having a simple clavicle ; the interclavicle is cruciform. 



This family comprises a large number of species, all of which are 

 inhabitants of the Xew World, which show great variety of form 

 and scaling. The Teiidce with Lacertoid or Varanoid appearance 

 pass, through Crocodilurus and Keusticurus, into the Cercosaurs (to 

 which the latter is nearer on account of its separated nasal plates, 

 although hitherto placed with the true Teioids). "VVe have then 

 several diverging series, the two principal being : — towards Iletero- 

 dactijlus through Artkrosaiira, and towards Copliias through Procto- 

 porus. On the other hand, Cophias resembles Heterodactijlus in the 

 position of the nostril, and the latter genus leads us through Pero- 

 dactylus to the Skink-like genera such as Ipliisa and Gymnoplitlial- 

 rniis, which all agree with Heterodactylus in the rudimentary con- 

 dition (or absence) of the inner finger. And, at last, the vermiform 

 Chalcidines by their scaling and cranial structure approach the 

 Amphisbajnoids. 



Synopsis of the Genera. 



I. Anterior nasal plates not separated by the fronto-nasal* ; limbs 

 well developed. 



A. Scaly portion of the tongue not much widened, and not or but 

 feebly emarginate posteriorly, frequently rctz*actilc into a 

 basal sheath. 



1. Ventral plates small, forming more than 20 longitudinal 

 series. 



* Separated by several small scales in Callopistes ; sometimes separated in 

 Teiut. 



