(195) 



10. A Revision of the Lizards of the Genus Nucras, Gray. By Gr. A. 

 BOULENGER, LL.D., D.Sc., F.R.S. (Published by permission of 

 the Trustees of the British Museum.) 



(With Plates VI-VII.) 

 INTRODUCTION. 



When, some twenty-five years ago, the late Dr. E. Klebs submitted 

 to me the oldest known Lacertid (Oligoceue) with the lepidosis 

 preserved through imbedding in amber, a careful comparison with 

 recent lizards led me to refer it to the genus Nucras, although the 

 essential generic character of the position of the nostril could not be 

 ascertained, my conclusion being based on an examination of the 

 digits and of the scaling of the gular and pectoral regions, which 

 agreed better with Nucras tessellata than with any other lizard with 

 which I was acquainted.* Since then I have made a more thorough 

 study of the Lacertidae from the point of view of their probable 

 evolution, and independent, correlative reasons have confirmed my 

 provisional identification so far that, quite apart from any palae- 

 ontological consideration, I am now inclined to regard Nucras as, on 

 the whole, the most primitive genus of the Lacertidae. 



At the time I examined the lizard in amber, the representatives of 

 the genus were believed to be confined to Africa no further north 

 than the Zambesi Basin, and my suggested identification may there- 

 fore have seemed somewhat risky from the standpoint of zoogeo- 

 graphy. We must, however, bear in mind that, in Tertiary times, 

 the general character of the reptile fauna of the northern parts of 



* Cf. R. Klebs, Schrift. Phys.-oek. Ges. Konigsberg, li., 1910, p. 227. As this 

 lizard has uot received a name I propose to designate it as Nucras succineus. 



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